Patent Application
20090116471
The invention relates to a method to improve the quality of using a service proposed to users of mobile telephone terminals by a service provider and/or a telecommunications' operator, such service relating to at least one type of multimedia data.
By “multimedia data” is meant here a photograph, a video, a sound file, an audiovisual file, a text file, a drawing(s) file, and/or one or several programme(s).
By “quality of using a service relating to a type of multimedia data” is meant here the quality of the multimedia data such as perceived by a user, the response time to a service as perceived by the user and/or the success rate of the service, for example the successful sending of the multimedia data.
The invention aims at overcoming the limitations resulting from at least one factor affecting the quality of using the service relating to the multimedia data. Such factors affecting the quality of use are included in the group comprising:
Thus, the method according to the invention includes the following steps:
It should be noted here that the fractions mentioned above can adopt any value comprised between 0 and 1.
With the invention, thus not only the quality of using the services relating to the multimedia data inside the mobile telephones can be improved, but also they can be extended, and the time necessary for receiving the services is reduced.
For example, when the multimedia data is an image such as a photograph, the process can be shared between the mobile telephone and the server or the process can be carried out inside the server.
In an embodiment, the method includes the following steps:
shall be defined, in the mobile telephone, instructions relating to the process having to be performed inside the server, such process being referred to hereafter as the “remote process”,
The instructions can include:
the method further including the step for the server to transmit, to the beneficiary of the service, the result of carrying out the instructions relating to the process.
According to a variant, the instructions relating to the process having to be carried out inside the server are defined in the server, particularly subsequent to communication with the mobile.
According to an embodiment, the fraction of the remote process includes at least one process contained in the group comprising:
According to an embodiment, the method includes, inside the mobile telephone, a multimedia data compression step, for example compression of the JPEG type, such compression step including a pre-process in order to optimise the multimedia data size, its compression rate applied and its format, such pre-processing depending on at least one of the parameters included in the group comprising: the type of service required, the network transmission specifications, the optimal compression curve according to the multimedia data size and the multimedia data compression type,
the multimedia data compression preferably being implemented within the frequency domain,
the method further including a decompression inside the remote server with, preferably, an elimination process for the artefacts or defects linked to the compression.
The optimal compression curve/size of the multimedia data is determined in the following manner:
a) depending on the type of service, shall be determined the necessary size for the final use of the data; for example, in the case of a photograph, the size for using the data is 2 mega pixels in order to print in 10×15 cm format, 50 kilopixels in order to display on the screen of mobile telephone terminal and 300,000 pixels in order to display on a computer screen; in the case where such service is not known, the size considered for use is the size of the original multimedia data, or in another embodiment, the maximum necessary for all known services,
b) shall be determined the maximum size of the file for transmitting the multimedia data according to the network capacity and the other data factors to be transmitted,
c) shall be determined the optimal rate for sampling using a chart defined in advance based on multimedia data (namely from the images illustrated), the chart providing a value for the sampling rate depending on the maximum file size,
d) shall be determined the compression parameters depending on the contents of the multimedia data; for example the compression of an image must be that much higher, the more details there are. In an embodiment, several ranges of compression parameters are tested in order to obtain a file size equaling, as far as possible, the size required for the data's final use.
In an embodiment, the multimedia data is stored inside the remote server without compression, or without additional compression, or with low compression, or with additional low compression, and is compressed for transmission to the mobile telephone where it undergoes a process depending on the service to be provided, or requested by the mobile telephone, the processed and compressed data transmitted being allocated a markup linked to the original multimedia data stored without compression inside the remote server in order to enable its subsequent use without compression or at a more reduced compression than the processed and compressed data transmitted. By “compression” is mainly meant reducing the size of the data and/or sub-sampling.
According to an embodiment, the remote server comprises a base for mobile telephone signatures in order to be able to identify the origin and the multimedia data to be processed and to determine the type of process for each type of multimedia data, the signatures being extracted from the multimedia data or being appended to the multimedia data. The signatures may belong to any one of the following categories:
According to an embodiment, the remote server occupies a position included within the following group:
The invention also concerns a mobile telephone terminal comprising:
means for improving the quality of using a service relating to photos, and/or video, and/or audio, and/or text, implementing at least one process for such data, such service being proposed by a service provider and/or a telecommunications' operator inside the mobile telephone,
such means for improving the quality of use comprising:
means for determining, a priori or in real time, according to at least one factor affecting the quality of use, a first fraction of the multimedia data to be processed inside the mobile telephone, a second fraction of the multimedia data having to be processed inside at least one remote server connectable to the mobile telephone, a first fraction of the process having to be performed inside the mobile telephone and a second fraction of the process having to be performed inside a remote server,
means to perform the process or processes thus determined inside the mobile telephone, and
means for transmitting to the remote server the multimedia data or fraction of data having to be processed inside such server.
According to an embodiment, the terminal includes means for determining, inside such mobile telephone, the fractions of the multimedia data to be processed and/or the fractions of the process having to be performed, and/or the means for receiving information relating to the said fractions from a remote server.
According to an embodiment, the terminal includes means for transmitting to the remote server the instructions relating to the process having to be performed inside such server.
In an embodiment, the terminal is such that the instructions include:
According to an embodiment, the means for determining the fraction of remote process having to be performed inside the server include the means for selecting such remote process when the process is included in the group comprising:
According to an embodiment, the terminal includes means for compressing the multimedia data, for example means of the JPEG type, such compression means including pre-processing means in order to optimise the size of the multimedia data, its compression rate applied and its format, such pre-process depending on at least one of the parameters included in the group comprising: the type of service required, the network transmission specifications, the optimal compression curve according to the size of the multimedia data and the multimedia data compression type,
the multimedia data compression preferably being implemented within the frequency domain.
The invention also concerns a mobile telephone telecommunications network server comprising means for improving the quality of using a service relating to at least one type of multimedia data, namely relating to photos, and/or video, and/or audio, and/or text, implementing at least one process for such data, the means for improving the quality of use including:
means for determining, according to a factor affecting the quality of using the service by the mobile telephone, a first fraction of the multimedia data which has to be processed inside the mobile telephone, a second fraction of the multimedia data which has to be processed inside at least one remote server connected to the mobile telephone via the network, a first fraction of the process having to be performed inside the mobile telephone and a second fraction of the process having to be performed inside at least one remote server,
means for transmitting the said fraction values to the mobile telephone, and
means for performing the fraction(s) of the multimedia data process having to be performed inside such server.
According to an embodiment, the server includes means for performing at least one of the processes included in the group comprising:
According to an embodiment, the server includes means for storing multimedia data without compression, or without additional compression, or with additional low compression in relation to the multimedia data received from a mobile telephone and for transmitting such compressed data to mobile telephones and in order to allocate a markup to such multimedia data.
According to an embodiment, the server comprises a base for mobile telephone signatures in order to be able to identify the origin and the multimedia data to be processed and to determine the type of process for each type of multimedia data,
the signatures being extracted from the multimedia data or being appended to the multimedia data.
In such a case, the signatures may belong to one of the following categories:
According to an embodiment, the remote server shall occupy a position included among the following group:
Other characteristics and advantages of the invention shall come to light in the description of some of its methods of embodiment, these being performed by referring to the sketches attached hereto whereby:
a illustrate the steps of a method according to the invention,
b, 2a, 2b, 2c, 3, 4, 5, 6, 7 and 8 refer to an embodiment example of the invention for a service sending postcards,
The examples described mainly refer to a mobile telephone terminal equipped with a picture-taking device, often known as a “photophone” or a “cameraphone”.
Using the Services
Using such terminals is tedious, especially when it concerns:
Image Quality
The image quality is limited due to the reduced dimensions, electricity consumption and mobile terminal costs.
The quality is variable depending on the terminal type and requires specific image processing. The image quality depends on the how the image is viewed. In particular, on a tiny screen many defects are invisible, while on a large-size screen or on a print-out, such defects become visible.
The images are highly compressed for the purpose of being stored inside the authorised pass-band, which produces artefacts during the decompression required for displaying or printing the images.
Thus we have particularly troublesome drawbacks which hinder the development of using photo services with a mobile telephone terminal due to such services being much less efficient than those linked to dedicated cameras.
Architecture
The calculation time for improving images is generally proportional to the size of the image, i.e. to the number of pixels.
Improving the quality of the image takes up considerable calculation time and thus electricity. The capacity of the processors integrated into the terminals increases less quickly than the number of pixels from the sensors.
The IT performance is limited and varies according to the terminal type.
Access to the IT performance is variable depending on the terminal type: certain terminals accept code written in C++, some only accept Java code (much slower for image processing than C++), others are not open to coding.
The local storage capacity is limited.
The size of the transmission pipes is limited. In France, it corresponds to 50 ko per message, passing gradually to 100 ko.
Images transit systematically by a server for the various services.
In order to resolve these problems, the invention improves the image quality and/or improves the design for use.
The method according to the invention intervenes prior to taking a picture and/or during picture-taking and/or after taking a picture.
Thus, as illustrated in
As a variant, and as described hereafter in relation to
In the example shown in
1. Services
1.1. The Various Services Considered Using the Image are:
1.2. For Each One of the Services:
Taking a picture and/or searching in an album and/or retouching with improvement of the picture taken (lessons, framing assistance, verification, etc.),
1.3. In Order to Send a Facsimile (Fax) from a Terminal, the Procedure is as Follows:
In order to send a facsimile from a terminal, the following procedure is also possible:
In order to send a facsimile from a terminal, it is also possible to use another procedure:
1.4. A Passport Photo Service Includes, in the Embodiment, the Following Steps:
Such framing assistance can be adapted to country standards for official documents.
Verifications can be automatic and/or manual.
Should rules not be observed:
Such message indicates, for example, how to retake a photo without the defect.
This service can be adapted to country rules for official documents.
1.5. Other Possible Services with a Cameraphone (or Photophone):
It is also possible to receive approval from a customer for choices emerging at a late stage, for the purpose of avoiding delays or errors of appreciation, for example, for authorising a more severe tree-felling than originally planned, showing the roots preventing the digging of a trench with the cameraphone.
2. Improving the Quality of the Image and Page Layout
After taking a picture, several techniques can be used to improve the image quality and the user design:
In the case of a process on a server, the process consists of:
In order not to correct the images twice over, these can be marked, for example, by adding or modifying the Exif or similar metadata.
It should be noted here that by metadata is meant data linked to the multimedia data and corresponding to information relating to the format of the file containing the multimedia data, and/or to the information relating to the compression, and/or to the origin of the data, and/or to the acquisition specifications. For example, in the case of a photograph, the acquisition parameters (such as the focus, the opening and the exposure time), and/or the results of calculation obtained using the multimedia data, such as the number of pixels.
Processing the image can be carried out in various ways:
a) No calculation is made locally (i.e. in the terminal) and the image is sent back to the user (i.e. terminal) after remote calculation (in a server).
b) Local calculation is made according to the terminal screen's resolution and a remote calculation is made for the image transmitted by the service.
c) Local calculation is made of the terminal screen's resolution and, for the image transmitted by the service, decompression is performed inside the server in addition to a clean-up of the compression artefacts prior to sending, the image processing transmitted for the service being able to be done locally and/or remotely.
In all events, the remote image transmission must be done by adapting the size and the compression to the service, as well as to the authorised message size, as described hereafter.
Similarly, the page layout can be performed locally or remotely:
a) No calculation is made locally, such calculation for the image transmitted by the service being done remotely and then returned to the user.
b) Local calculation is made according to the terminal screen's resolution and a remote calculation is made for the image transmitted by the service.
c) Local calculation is made of the terminal screen's resolution and, for the image transmitted by the service, decompression is performed inside the server in addition to a clean-up of the compression artefacts prior to sending.
Of course, the method described above can be applied to other types of multimedia data, namely relating to video, and/or audio, and/or text.
Thus can be obtained a method and a system to improve the quality of using a service, implementing at least a process, relating to at least one multimedia data, namely relating to photos, and/or video, and/or audio, and/or text, such service being proposed by a service provider and/or a telecommunications' operator inside a user's mobile telephone via a network.
Let us be reminded that this process is adapted to overcome the limitations resulting from at least one factor, affecting the quality of use, such as:
Thus, the method includes the following steps:
so that, for the user, the quality of the service is increased, namely:
For the service provider and/or the telecommunications' operator, new services can be provided.
This method can further include the following steps:
Such instructions may include:
The method further includes the step, for the server, to transmit the results of carrying out the instructions to the beneficiary of the service.
By “service” is particularly meant:
By “photo” is particularly meant:
By “process”, also called “correction”, is particularly meant:
By “IT resources” is particularly meant:
By “transmission specifications” is particularly meant:
By “identifier” is particularly meant:
By “code” is particularly meant:
By “beneficiary” is particularly mean:
By “instruction” is particularly meant, the data described in this patent request.
2.1. Types of Image Processing
The processes made to the images inside the terminal and/or on the server can be the following:
Removing all or part of the defects from the restitution means: terminal screen, computer screen, printing means.
2.2. Instructions for Remote Process
It is possible to transfer a part of the processes depending on the terminal's capacity, on the memory capacity, on the image size, on the possibility to programme the terminal in C++ as opposed to Java programming, which is badly adapted for processing multimedia data, and on the type of service desired. For the user, processes remain in real time for operations requiring feedback to such user.
Information enabling to describe the transferred process (for each image, or once and for all) must be transmitted, namely:
a) The type of improvement process to be made on the server. This concerns, for example:
Even if no process is to be performed, such instruction must be transmitted, possibly by default.
b) Retouching to be made to the image (rotation, cropping, adding a frame, etc.), which enables retouching inside the terminal on an image reduced to the size of the screen and subsequent retouching when at the final size.
c) The types of services and their recipient(s):
d) Output editing indications:
The editing data must be separate from the physical format in order to enable printing in several formats. The size and position of the text and image elements are determined downstream.
e) The contents:
Such contents can be transmitted as an address and/or metadata.
The contents can be described by a format. Such format can be open (standard and/or extensible); it can be an extension of the MMS “SMIL” format. It must be compatible with all types of dispatch protocol (MMS, http, WAP, e-mail, etc.) and thus compatible with the existing networks.
2.3. Recognition of the Picture-Taking Device.
According to an embodiment, the remote server comprises a base for mobile telephone signatures in order to be able to recognise the origin of the multimedia data to be processed and to determine the type of process for each type of multimedia data, the signatures being extracted from the multimedia data or being attached to the multimedia data.
In order to recognise the origin of the multimedia data, an analysis of the multimedia signature is made, which enables to apply the adapted process.
Now, we are going to describe an embodiment example when the multimedia data is a photo.
The signature information included in the image can be used: JPEG comment, Exif, quantification table, or other metadata, for the purpose of constituting a base for the signatures with, for each signature, the type of correction to be made.
This is particularly interesting for the case where the terminal having taken the photo is not known by the processing server, either because the photo does not originate from the issuing terminal, or because the type of issuing terminal (“user agent” or equivalent) is unavailable.
Automatic recognition of the device capturing the image can be activated according to the following steps:
The base of signatures is updated regularly and is preferably done prior to the device being put on the market in order minimise the number of unknown signatures and thus of non-adapted corrections.
Several types of terminals may have the same signature. In such a case, a compatible correction can be created for such different terminals.
It should be reminded here that it is possible to use the same correction for every terminal type. This solution has the advantage of being simple but does not optimise correction.
Certain terminals can have several signatures: in such a case, the various signatures are added to the base.
The signature is composed of all or part of the following information:
In order to determine correction, particularly in the event of doubt, can also be used:
An example of the signature coding is as follows:
Auto#13,9,9,13,18,20,24,23#211#0#1280×960#tutu|titi|glouglou#0220#SO505i#DoCoMo#
In this example, the various fields are separated by the “#” sign and are explained below:
1. Auto: information of the device type which can contain either “auto” to mean that no information is available, or can contain a device identifier determined otherwise, for example as described above using the “user agent” or from a message signature itself.
2. 13,9,9,13,18,20,24,23: contains the first n coefficients from the luminance quantification table (channel Y), such as given in the JPEG heading.
3. 211: format of the JPEG sub-sampling in number form comprising 3 or 4 figures.
4. 0: JPEG tag value “saw_JFIF_marker” (which equals 1 or 0).
5. 1280×960: height and width of the image in number of pixels.
6. All or part of the JPEG comment.
7. The following fields contain information on Exif:
2.4. Transferred Processing of an Image
Preferably, in order to code the images for their transmission, a JPEG standard compression programme is used, which is implemented in all telephones; however, another format may be used. The image processing steps are as follows:
Everything is decompressed by eliminating the compression artefacts; then:
The transfer is performed via MMS, surcharged MMS, e-mail, http, WAP or other means.
The message can be sent to a third party and/or used on the issuing terminal, for example to visualise the outcome or to receive advice.
2.5. Local Processing of a Service
Preferably, in order to code the images for their transmission, a JPEG standard compression programme installed in all terminals is used; however, another format can also be used. The image-processing steps are as follows:
a) Possibly pre-processing.
b) Then:
c) Mark the image to avoid applying the same processes several times over;
possibly optimise the image size, the compression rate, and the image format depending on the type of service and the pipe size:
d) For services using a large-size image:
Transfer can be performed directly towards the final user (except in the case of a postcard) or via a service provider.
2.6. Storage
In an embodiment, the multimedia data is stored without additional compression or with low additional compression inside the remote server and is compressed for transmission to the mobile telephone, and it undergoes a process depending on the service to be provided, or requested by the mobile telephone, the compressed and processed data transmitted being allocated a markup linked to the original multimedia data stored without compression inside the remote server in order to enable its subsequent use without compression or with a lower compression than the processed and compressed data transmitted. By storage without compression is meant storage prior to compression or size reduction, or failing that with low compression and/or a slight size reduction.
In the case where the image is compressed or reduced prior to transmission to the recipient for the purpose of optimising output, images can be stored inside the server prior to compression or size reduction in order to allow the use of all the services with maximum quality by the recipient of a message. Such facility enables in fact to use services at a later date for this same image: for example, terminal A sends terminal B an image by MMS, and terminal B transmits this image towards a postcard service based on the image stored inside the server.
In order to do so, the following steps are necessary:
When the image transits again via the server:
Currently, a server's hard disk is able to store approximately 5 million images.
The advantages obtained by such storage are the optimal quality, a reduced pass-band for transmission, and compatibility with all types of terminals.
2.7. System
The remote server, also called “correction server”, can be positioned:
The following terminal and server combinations are possible:
The processes providing feedback to the user can be achieved:
2.8. Adapting the Image to the Size of the Pipe
The telecommunications' operators limit the size of messages transmitted, for example by MMS.
The size of an image file depends upon the contents of the image. For a given number of pixels and a given perceived level of quality, an image containing much detail will generate a file considerably larger than an image containing less detail.
It is thus necessary to automatically adapt the level of quality to enable the use of a service in all cases and not to exceed the pass-band allocated by the operator.
Several ways of adapting this level of quality exist, with the main point depending upon the use and thus the service type.
When using a service, the images adopt the following pattern:
a) Taking a picture and possible compression.
b) Pre-processing in order to optimise the size of the multimedia data, its compression rate applied and its format: adapting the pass-band allocated by the operator, by reducing the size of the file transmitted, such reduction being performed via a possible reduction in the number of pixels, and/or an increase in the rate of compression.
c) Decompression with, preferably, a reduction of artefacts.
d) Change in the number of pixels for the purpose of adapting to the screen or the printer used for the service (final number of pixels).
In order to reduce the file size, a compromise exists between the number of pixels and the compression used:
The file size reduction operations can take place:
2.9. Application Examples
Examples of process-distribution are set out below:
a) Application with a 3G network
Such network enables fast terminal-server exchanges. It is thus possible to carry out processes inside the server and to rapidly display the outcome on the telephone.
Hence it is possible to work with any IT performance on the terminal and with a high number of pixels.
b) Application with a 2.5G and a top-of-the-range telephone (“Smartphone” in English).
The network does not enable fast terminal-server exchanges. However, the terminal has a high IT performance.
It is thus possible to carry out image processing inside the terminal according to the screen size in order to show a preview to the user and to rapidly display the outcome on the telephone.
It is thus possible to carry out full resolution processing on the server without requiring feedback towards the user.
c) Application with a 2.5G network and a middle-of-the-range telephone (“Featurephone” in English).
The network does not enable fast terminal-server exchanges.
The terminal has limited IT performance and exchanges are slow. The availability of previews for the user shall be more limited, although the other advantage (design, accessibility to services, etc.) are maintained.
It is thus possible to carry out processes inside the server by limiting feedback towards the user.
3. Photography-Text Solution (FotoText+component)
The invention allows for a component, called “FotoText+”, which is a text scanner enabling to transform a photo taken of any document “of the binary type”, for example comprised of strokes on a clear background, particularly a handwritten text, an outline drawing, map or sketch, a printed text.
This component corrects the paper defects (background clean-up): the paper's shading, squares or lines, folds, stains, crumpling, and, of course, the camera and lighting defects. This can be done by extracting information above a threshold.
It optimises the contrast level.
It performs an automatic correction of the focussing “close-up blurring”, for example by applying an unblurring mask. Indeed, cameraphones are programmed for 80 cm sharpness to infinity and, in general, do not have auto-focus. However, the photo of a text is taken at a distance of approximately 15 cm, i.e. within the blur range of the cameraphone.
If this defect is hardly sensitive to very low resolutions (such as that on a screen: 160×120, or CIF), it is particularly sensitive as of 300,000 pixels (VGA).
It also corrects the calorimetric defects.
It is compatible with very high compression. Thus, a text photo representing approximately 25 ko, only represents a maximum of 5 ko after compression—in order to optimise transfer.
After decompression, then processing, the image is put back into printing format for an improved superimposition on a background: enlargement up to 300 points per inch or according to the format of the final document.
The component produces level grey strokes on a uniform background.
It can be used in various manners:
For example, for a postcard, the user takes two photos:
a) the photo for the front side of the postcard, and
b) the photo of a written/drawn text/graphic on a piece of paper.
A user interface enables to position the text/graphic onto the front-side of the photo; a local or remote terminal screen resolution process enables to display a preview, thus facilitating the work of the user.
The photo of the text/graphic is processed, cleaned by eliminating the non-uniform lighting zones to enhance readability, cleaned on its background and printed on the front-side of the photo.
In the case of a photo, particularly a passport photo, the background cleaning consists of making uniform all parts of the photo other than the actual person photographed, for example by detecting the outline of the face and filling the surrounds with a uniform colour.
4. Examples of Services
Described below, using
The figures illustrate the various screens (man/machine interface) of the terminal when using this service.
Screen 10 illustrated in
It is also possible to activate the “options” menu which then displays a screen 12 enabling the user to select the action, the preferences, assistance, or even to quit the service.
When selecting preferences, shown in the example in
On the screen 14 in
On the screen 16 (
On the screen 18 of
On
When choosing such “open” command, or when selecting the creation and sending of a new postcard on
The screen 30 illustrated in
When choosing the “front side” tab (
When selecting “Choose a page layout”, a choice is then provided between several types of page layouts, such page layouts differing in colour, in style, in size, etc.
If the user chooses the option “Create a new page layout”, a series of options are proposed which, in the example, are: the choice of the frame colour, the thickness of the frame, and the choice of a card with rounded corners and a choice of styles.
When the user clicks on the “text” tab of the screen 30 shown in
When choosing the “new text” option, the man/machine interface switches to text creation with standard input or semi-automatic input, which consists of allowing several fields for the text and reusing, in each one of the fields, texts already memorised. The first field is the header field which refers to the recipient: “Dear friend”, “Dear Mum”, etc. A second field concerns the body of the text: “It's fine today”, “Great holidays!”, etc. A third field concerns the closing of the text including the formal ending and a fourth field includes the signature.
When selecting the “photo-text” option, a screen (not illustrated) is then displayed to inform the user that he/she has to take a photo of a text, for example handwritten, with instructions for correctly taking a text photo, such as “make sure you are quite parallel” and “try to have uniform lighting”.
In an embodiment, a rectangular framing is displayed on the screen and enables to determine, depending on if it is deformed or not, whether the photograph is taken with the correct angle.
Once the text has been composed or photographed; the user can move on to the next step corresponding to the “reverse side” tab of
The choice of the page layout, which can be found, for example, in the terminal's memory, consists, in an embodiment, of choosing the type of postage stamp to be used and corresponding, for example, to the place where the photo was taken. It can also consist of choosing the background colour.
For creating a new page layout, a choice of fonts, a size of font, an overall colour and stamp are all proposed.
Preferably, when the post code is indicated, the corresponding town automatically appears, and reciprocally, when the town is indicated, the post code is automatically shown.
It is also possible to choose several recipients for a same postcard.
If the postcard is incomplete, a screen will mention that such postcard is not complete and will ask to choose an image, a recipient and a text; it will also indicate that a default front-side page layout (image) has been used and that, similarly, a default reverse-side page layout (text) has been used.
If the postcard is complete, then the sending screen indicates that the postcard is ready to be sent and proposes the user to save it as a template.
Finally, after dispatch, a screen shows that the postcard has been sent and proposes the user to send the same card to another recipient.
5. Adapting the Data to be Transmitted to the Network Transmission Capacity
The capacity of the sensors in cameraphones is constantly increasing and widely exceeds the pass-band containing the transmission protocols. For example, a VGA sensor provides 300,000 pixels and each pixel uses one octet in order to code each one of the colour channels, which provides a gross image of approximately 900 ko. However, most terminals are only capable of sending files, once compressed, of 30 to 50 ko, i.e. approximately 3 to 5% of the initial data in the case of a VGA sensor.
Based on such observation, the invention proposes a method which enables to optimise the image quality transmitted due to a protocol which enables to choose, in light of such optimisation, the rate of the sub-sampling, and the compression parameters, namely of the JPEG type.
It is in fact known that, in order to reduce the image file size, sub-sampling can be done on the one hand, while it can be compressed on the other using a compression algorithm, such as the JPEG algorithm.
Subsequent sub-sampling and re-sampling reduce the resolution and entail a loss of detail as well as aliasing.
Furthermore, the JPEG compression leads to a loss of information and causes the appearance of artefacts (defects), which are all the more important as the compression rate is high.
Having said that, the loss of resolution caused by re-sampling may no longer be corrected. On the other hand, the artefacts caused by JPEG compression have an organised and known distribution which enables them to be corrected within a certain limit. Such correction is performed, for example, by smoothing the unit edges as described in the JPEG standard or even by an algorithm known as the “JPEG CLEANER” enabling to decompress and correct such defects.
In order to determine the compression rate and the sampling rate, the chart shown in
Such chart comprises three curves corresponding to three different images.
The chart is obtained in the following manner: three test images are selected which represent at the outset a 1 mega pixel definition.
Using such images, copies compressed at different rates are generated, thus enabling to obtain files of a given size: 200 ko, 150 ko, 100 ko, 80 ko, 60 ko, 55 ko, 50 ko, 45 ko, 40 ko, 35 ko, etc., re-sampled in advance, the sampling rate being by 90%, 80%, 70%, 60%, etc., the sampling rate being the same whether being in horizontal or vertical direction.
The images are then categorised by file size and each group of files is thus comprised of images having the same size, though with varying definitions.
In order to be able to compare the different images thus obtained, such images were put back into the definition of the original by way of an interpolation calculation of the bi-cubic type.
Next, for each series of images, an experienced viewer observed the various images on a computer screen and determined the image that he/she judged the most satisfactory compared with a file of similar size, while noting of course, the sub-sampling rate and the corresponding compression factor.
It was noted that the association of the JPEG compression to image re-sampling enables to obtain better results than either of the methods used separately.
Hence it was noted that the chart in
In the chart shown in
Based on a 1 mega pixel image which represents approx 3 Mo in size without compression, for the purpose of obtaining a 30 ko file, it is preferable to sub-sample the image by 50% (which corresponds to a 4-factor reduction in the number of pixels) prior to image compressing. To obtain a 50 ko file, it is advisable to sub-sample the image by 70% (i.e. a 2-factor reduction in the number of pixels) prior to image compressing. Finally, for a file exceeding 130 ko, it is preferable to use only a JPEG compression, without sub-sampling.
In practice, the mobile telephone terminal contains in the memory the charts shown in
Thus, in order to determine the file that should be sent over the network, an algorithm linked to the file size is programmed inside the mobile telephone terminal, which can be transmitted by the latter over the network. This file size in abscissae in
However, the compression rate obtained can provide a file size exceeding that supported by the network, as, for a given compression rate, the final file size shall depend upon the amount of details contained in the image. This is why, in such a case, the algorithm selects a higher compression rate B′, which enables to select a corresponding sampling rate due to the 50 curve of
Of course, the optimal compression curve depending on the multimedia data size can be represented inside the terminal's memory in the form of charts from
And of course, only the necessary part of the optimal compression curve could be represented inside the terminal's memory depending on the size of the multimedia data. The necessary part being, for example, the extract corresponding to the maximum file sizes able to transit by the networks of the various telephone operators.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0451132 | Jun 2004 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR05/50429 | 6/8/2005 | WO | 00 | 2/2/2007 |
