Patent Application
20120033103
As the field of digital image capture devices matures, the resolution of captured images continues to increase. Where it was initially common for image capture devices such as mobile telephones and still and video cameras to have image sensors of 1-2 megapixels, it is now common for these same devices to provide images having at least 3-5 megapixels. While the increased resolution provides higher quality pictures/images for the user, it also increases the amount of data that must be transported and processed within the device itself.
Referring to
During normal operation image capture device 100 captures a number of full-resolution images each second (e.g., 15 images per second). A low-resolution replica of each full-resolution image (hereinafter referred to as a “preview image”) is then generated and presented to the user through, for example, display 140. At some point in time, a user provides input (e.g., via user input device 145) indicating that one of the images is to be retained. At that time, the full-resolution image corresponding to the preview image being displayed on display 140 at the time the user indicates image capture should occur is encoded in a final format (e.g., the Joint Photographic Experts Group, or JPEG, format) and written or stored to non-volatile storage such as a solid-state or magnetic disk unit (e.g., memory 115).
Referring to
Table 1, identifies the bandwidth requirements for data flow 200 under the following assumptions: (1) the full-resolution image is 2048×1536 pixels (3 megapixels) and is encoded in 4:2:0 YCbCr format using 1.5 bytes per pixel; (2) the preview image is 852×640 pixels and is also encoded in 4:2:0 YCbCr format using 1.5 bytes per pixel; and (3) the image capture rate is 15 frames per second. Table 2, identifies the bandwidth requirements for data flow 200 under the same assumptions except that the full-resolution image is now 2592×1936 pixels (5 megapixels).
A comparison of Tables 1 and 2 clearly show that as the resolution of image capture devices increase, so too does the needed internal bandwidth. Thus, to facilitate the use of increased image resolution devices, it would be beneficial to provide a mechanism to reduce the amount of data that must be transferred during image capture operations.
As the resolution of digital image capture devices increase, the bandwidth needed to support this increased resolution is becoming increasingly difficult to support. To reduce the problems associated with run-time bandwidth requirements (e.g., the continuous capture of full-resolution and display or preview images), it may be beneficial to obtain full-resolution and display-resolution or preview images at the same time from the image capture circuitry—writing both to memory at virtually the same time. The display resolution image may then be delivered to a display unit directly without the need for additional memory operations on the full-resolution image. Only when a user indicates they wish to capture an image need additional memory operations on the full-resolution image be performed. The savings in run-time bandwidth over the prior art can be substantial.
In one embodiment an image capture device and method are described that: receive full-resolution RAW and preview images representing a scene from an integrated sensor package; stores the full-resolution RAW and preview images in a memory; and transfers the preview image from the memory to a display device for display. When user input is received indicating the desire to capture an image associated with the currently displayed scene (e.g., corresponding to the currently displayed preview image), the full-resolution RAW image may be encoded into any desired format, whereafter the encoded image may be stored in memory.
Techniques are described that can dramatically reduce the amount of data transport required in an image capture device. As the resolution of digital image capture devices increase, the bandwidth needed to support this increased resolution is becoming increasingly difficult to support. To reduce the problems associated with run-time bandwidth requirements (e.g., the continuous capture of full-resolution and display or preview images), it may be beneficial to obtain full-resolution RAW and display-resolution or preview images at the same time from the image capture circuitry—writing both to memory at virtually the same time. The display resolution image may then be delivered to a display unit directly without the need for additional memory operations on the full-resolution RAW image. Only when a user indicates they wish to capture an image need additional memory operations on the full-resolution RAW image be performed. The savings in run-time bandwidth over the prior art can be substantial.
In the following description numerous specific details are set forth in order to provide a thorough understanding of the inventive concept. It will be apparent to one skilled in the art, however, that the invention may be practiced without these specific details. In other instances, structure and devices are shown in block diagram form in order to avoid obscuring the invention. It will be appreciated that in the development of any actual implementation (as in any development project), numerous decisions must be made to achieve the developers' specific goals (e.g., compliance with system- and business-related constraints), and that these goals will vary from one implementation to another. It will also be appreciated that such development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the image processing field having the benefit of this disclosure.
References to numbers without subscripts are understood to reference all instance of subscripts corresponding to the referenced number. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.
Referring to
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Table 3, identifies the bandwidth requirements for data flow 400 under the following assumptions: (1) the full-resolution RAW image is 2048×1536 pixels (3 megapixels) and is encoded using 2 bytes per pixel; (2) the preview image is 852×640 pixels and is encoded in 4:2:0 YCbCr format using 1.5 bytes per pixel; and (3) the image capture rate is 15 frames per second. Table 4, identifies the bandwidth requirements for data flow 400 under the same assumptions except that the full-resolution RAW image is now 2592×1936 pixels (5 megapixels).
Table 5 shows the savings in run-time bandwidth afforded by an image capture process in accordance with various embodiments assuming: (1) the preview image is 852×640 pixels and is encoded in 4:2:0 YCbCr format using 1.5 bytes per pixel; and (2) the image capture rate is 15 frames per second. As used herein, the phrase “run-time bandwidth” refers to the bandwidth required during image capture operations before a user indicates they wish to take a picture (e.g., during operations 405a/405a′-410n). As can be seen, the savings can be significant.
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Image capture process 500 in accordance with this disclosure may be performed by a programmable control device executing instructions organized into one or more program modules. Storage devices suitable for tangibly embodying program instructions (e.g., memory 310) include, but are not limited to: magnetic disks (fixed, floppy, and removable) and tape; optical media such as CD-ROMs and digital video disks (“DVDs”); and semiconductor memory devices such as Electrically Programmable Read-Only Memory (“EPROM”), Electrically Erasable Programmable Read-Only Memory (“EEPROM”) and flash devices.
Various changes in the materials, components, circuit elements, as well as in the details of the illustrated operational methods are possible without departing from the scope of the following claims. For instance, ISP 305 may include other functionality not discussed herein. Further, encoder circuit 320 functionality may be incorporated within ISP 305. In addition, the resolution of sensor 345 is not limited to 3 or 5 megapixels—these values being used here simply for illustrative purposes. Finally, it is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments may be used in combination with each other. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention therefore should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.”
The present application is related to the commonly-owned application entitled “Image Capturing Device Having Continuous Image Capture,” filed on Jun. 5, 2009 having Ser. No. 12/479,756; which is hereby incorporated by reference in its entirety.
