Wide dynamic range image capturing apparatus

Abstract

A memory control block performs in parallel a process of writing a current frame of image data captured by an image capturing device into a system shared memory, a process of reading out a previous frame of image data stored in the system shared memory, and a process of writing combined image data generated in an image combining block into the system shared memory.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a wide dynamic range image capturing apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating an output waveform when an electric charge accumulation period is controlled on a frame-by-frame basis.

FIG. 3 is a diagram illustrating an enlarged output waveform of a dynamic range.

FIG. 4 is a block diagram illustrating a configuration of a wide dynamic range image capturing apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a block diagram illustrating a first form of image signal processing.

FIG. 6 is a block diagram illustrating a second form of image signal processing.

FIG. 7 is a block diagram illustrating a configuration of a conventional wide dynamic range image capturing apparatus.

FIG. 8 is a diagram for describing an operation of the conventional image capturing apparatus of FIG. 7.

Claims

1. A wide dynamic range image capturing apparatus comprising: an image capturing device for capturing image data having an electric charge accumulation period varying every a frame;a preprocess block for performing DC adjustment, gain adjustment, and gamma characteristics adjustment with respect to the image data;a data storage memory for storing the image data;a memory control block for controlling a write or read operation of the image data with respect to the data storage memory;an image combining block for performing a combining operation process with respect to two frames of image data having the different electric charge accumulation periods to generate combined image data; andan image processing block for performing video signal processing with respect to the combined image data,wherein the memory control block can perform in parallel a process of writing a current frame of image data captured by the image capturing device into the data storage memory, a process of reading a previous frame of image data stored in the data storage memory, and a process of writing the combined image data generated in the image combining block into the data storage memory.

2. The wide dynamic range image capturing apparatus of claim 1, wherein the image capturing device successively outputs image data having an electric charge accumulation period varying every a frame, where two frames constitute one cycle, and the memory control block can perform in parallel a process of writing the image data captured by the image capturing device into the data storage memory during a frame period, a process of reading the image data stored in the data storage memory during the frame period, and a process of writing the combined image data generated in the image combining block into the data storage memory every a frame.

3. The wide dynamic range image capturing apparatus of claim 1, comprising: a dedicated frame buffer memory for storing the image data; anda dedicated memory control block for controlling a write or read operation of the image data with respect to the dedicated frame buffer memory,wherein the image capturing device captures a long-time exposure frame and a short-time exposure frame each every other frame, to successively output image data having an electric charge accumulation period varying every a frame,the dedicated memory control block reads a previous frame of image data stored in the dedicated frame buffer memory while writing a current frame of image data captured by the image capturing device into the same address, andthe image combining block stores combined image data generated by performing a combining operation process with respect to the current frame of image data and the previous frame of image data, into the data storage memory.

4. The wide dynamic range image capturing apparatus of claim 1, comprising: a dedicated frame buffer memory for storing the image data; anda dedicated memory control block for controlling a write or read operation of the image data with respect to the dedicated frame buffer memory,wherein the image capturing device captures a long-time exposure frame and a short-time exposure frame each every other frame, to successively output image data having an electric charge accumulation period varying every a frame,the dedicated memory control block reads a previous frame of image data stored in the dedicated frame buffer memory while writing a current frame of image data captured by the image capturing device into the same address, andthe image combining block inputs combined image data generated by performing a combining operation process with respect to the current frame of image data and the previous frame of image data, directly into the image processing block so as to successively perform video signal processing.

5. The wide dynamic range image capturing apparatus of claim 1, comprising: two dedicated frame buffer memories for storing the image data; anda dedicated memory control block for controlling a write or read operation of the image data with respect to the dedicated frame buffer memories,wherein the image capturing device captures a long-time exposure frame and a short-time exposure frame each every other frame, to successively output image data having an electric charge accumulation period varying every a frame,the dedicated memory control block switches and writes data of the long-time exposure frame and data of the short-time exposure frame on a frame-by-frame basis into one of the two dedicated frame buffer memories while reading the other dedicated frame buffer memory during a frame period, andthe image combining block stores combined image data generated by performing a combining operation process with respect to the current frame of image data and the previous frame of image data, into the data storage memory.

6. The wide dynamic range image capturing apparatus of claim 1, comprising: two dedicated frame buffer memories for storing the image data; anda dedicated memory control block for controlling a write or read operation of the image data with respect to the dedicated frame buffer memories,wherein the image capturing device captures a long-time exposure frame and a short-time exposure frame each every other frame, to successively output image data having an electric charge accumulation period varying every a frame,the dedicated memory control block switches and writes data of the long-time exposure frame and data of the short-time exposure frame on a frame-by-frame basis into one of the two dedicated frame buffer memories while reading the other dedicated frame buffer memory during a frame period, andthe image combining block inputs combined image data generated by performing a combining operation process with respect to the current frame of image data and the previous frame of image data, directly into the image processing block so as to successively perform video signal processing.

7. The wide dynamic range image capturing apparatus of claim 1, wherein the image combining block causes an operation bit width of luminance signal processing and color signal processing in the generated combined image data to be larger by 1 bit than a bit width of captured image signal data, and stores the combined image data into the data storage memory.

8. The wide dynamic range image capturing apparatus of claim 4, further comprising: an output signal select block for receiving the image data output from the preprocess block and the combined image data output from the image combining block, and selectively outputting one of the image data and the combined image data.

9. The wide dynamic range image capturing apparatus of claim 4, wherein the image combining block reads the previous frame of image data stored in the dedicated frame buffer memory and causes a gain of the previous frame of image data to be 0, and performs a combining operation process with respect to the current frame of image data and the previous frame of image data.

10. The wide dynamic range image capturing apparatus of claim 1, wherein the preprocess block performs different characteristics adjustments with respect to two frames of image data having the different electric charge accumulation periods, respectively.

11. The wide dynamic range image capturing apparatus of claim 1, wherein the image combining block performs a combining operation process with respect to two frame of image data having the different electric charge accumulation periods to generate combined image data before performing a nonlinear gain process with respect to the combined image data.

12. The wide dynamic range image capturing apparatus of claim 1, further comprising: a highlight detecting block for detecting a highlight portion in an image read out every a frame,wherein the image combining block, when the highlight detecting block detects that a sum obtained by counting data having a predetermined threshold or more in an area becomes any set value or more, switches normal image capturing to wide dynamic range image capturing automatically or by a feedback setting process using a CPU.

13. The wide dynamic range image capturing apparatus of claim 12, wherein the highlight detecting block detects a highlight portion in a long-time exposure data image read out every other frame, and the image combining block, when the highlight detecting block detects that a sum of area data having a predetermined level or more becomes any set value or less, switches wide dynamic range image capturing to normal image capturing automatically or by a feedback setting process using a CPU.

14. The wide dynamic range image capturing apparatus of claim 13, wherein the highlight detecting block detects a highlight portion in a short-time exposure data image read out every other frame, and the image combining block, when the highlight detecting block detects that a sum of area data having a predetermined level or more becomes any set value or less, switches wide dynamic range image capturing to normal image capturing automatically or by a feedback setting process using a CPU.

15. The wide dynamic range image capturing apparatus of claim 1, further comprising: a motion detecting block for performing motion detection based on a correlation between a plurality of images read out every a frame,wherein, when a motion detection level of a set area of interest in the image data becomes a predetermined level or less, normal image capturing is switched to wide dynamic range image capturing automatically or by a feedback setting process using a CPU.

16. The wide dynamic range image capturing apparatus of claim 15, wherein the image combining block, when the motion detection level of the set area of interest in the image data becomes the predetermined level or more, switches wide dynamic range image capturing to normal image capturing automatically or by a feedback setting process using a CPU.

17. The wide dynamic range image capturing apparatus of claim 15, wherein the motion detecting block generates a motion detection signal using a motion vector of an MPEG function as input information, and the image combining block switches between normal image capturing and wide dynamic range image capturing based on the motion detection signal.

18. The wide dynamic range image capturing apparatus of claim 1, wherein a preprocess of performing an image capturing operation in which a current frame of image data captured by the image capturing device and a previous frame of image data stored in the data storage memory are subjected to a combining operation process in the image combining block and resultant data is stored into the data storage memory, and a post-process of reading out and subjecting the combined image data generated in the image combining block to video signal processing, are performed in parallel by an asynchronous memory control operation.