Exception Handling of JPEG ssive JPEG in the embedded system

Reprinted please indicate the source and the author contact: http://blog.csdn.net/mimepp
Contact information: Yu Tao <yut616 at Sohu dot com>

In JPEG, there is a type of progressive image that you may have seen on the network, that is, the one that first appears a blurred image and then gradually becomes clearer. Compared with baseline JPEG, this image has some advantages in network transmission, allowing users to see the image first and provide a better user experience UX.
Generally, baseline JPEG is stored in the top-to-bottom scan mode, while the progressive method is to divide the file into multiple scans. During the first scan, use a very low quality setting, so that the occupied space is very small. Next, the scan will gradually increase the quality, and each scan will be added to the existing data, so that the file size is basically the same as that of baseline. In general, JPEG ssive JPEG organizes the same data into a slightly more complex order.

However, when progressive JPEG is used for decompress, it will occupy a large amount of memory. In the embedded system, it will cause out-of-memory.
Especially when it exceeds 720*480, the occupied memory sometimes reaches 16 Mb.Fopen
Performance_std_error
Setjmp
Pai_create_decompress
Performance_stdio_src
Jpeg_read_header, which must be followed by the progressive type and handle exceptions. For example, the returned results are not supported.
Jpeg_start_decompress, which occupies a large amount of memory.
Pai_read_scanlines...
Pai_finish_decompress
Pai_destroy_decompress
Fclose

You can also make a judgment on the processing of jcs_cmyk/jcs_ysi-type in the same place. Jcs_cmyk, /**/ /**/ /**/ /*C/M/y/K*/
Jcs_yudf /**/ /**/ /**/ /*Y/CB/Cr/K*/

CMYK is generally used in the printing field. CMYK represents four ink colors used for printing. Its full name is cyan-magenta-Yellow-black, c Indicates cyan, M indicates Magenta, y indicates yellow, and K indicates black. In painting, in theory, only the first three colors can be used to match all colors, but in fact, black is hard to match, often with dark gray or dark gray blue, therefore, black is added to the printing, so that the dark part is black enough to be pure. It is also called the four-color printing mode. In addition, because the concentration of each color changes from 0% to 100%, the color that can be matched is much less than that of RGB.
the original color of the leaves is not green. It is because the leaves absorb light other than green light (fading) and only reflect the color effect of the green light to the human eyes. Therefore, CMYK is also called the fading mode.
In addition, some images in CMYK format have EXIF thumbnails.
the value of ykipper is luminance brightness, chroma color, chroma, and black. It is an uncommon format defined by Adobe.