JPEG image format

JPEG image format JPEG (Joint Photographic Experts Group) is the most common digital image formats. .JPEG wide range of application, including the world wide web browser, image processing software and so on. .JPEG format used in digital camera photos, it can compress the photo file size to 10% to 20%. .Compared to the original uncompressed image, JPEG image format <P> </ P> <P> JPEG (Joint Photographic Experts Group) is the most common digital image formats. .JPEG wide range of application, including the world wide web browser, image processing software and so on. .JPEG format used in digital camera photos, it can compress the photo file size to 10% to 20%. .Compared to the original uncompressed image, JPEG image quality degradation and loss of detail is not obvious. .</ P> <P> theoretical summary </ P> <P> In short, JPEG the image information (color and other details) to re-schedule, which compressed the color details of the degree of compression than the large, because our eyes on .details of the change in the color change than the high degree of sensitivity. .Then, JPEG to the details of the information classified as meticulous details and coarse detail. .As our eyes on the rough details of the changes in more sensitive, so fine details will be discarded. .JPEG is through a complex series of mathematical operations and the compression method, without serious damage to the case of quality, compressed image size. .The more complicated mathematics and compression methods, without knowledge of the reader may feel that obscure, so we did not in the glossary which records the content. .Interested readers can refer to a more professional image processing books and articles. .</ P> <P> instance </ P> <P> JPEG image file size and image quality between a good balance. .JPEG compressed image, the image processing is divided into one square area, area size is 64 pixels (8 x 8), each region is independent compression. .In the case of small degree of compression, the edge of each region there is a "hair-like" unnatural signs; when the compression level increases, more and more obvious of these signs, we can even see and distinguish the various regions. .Detailed Look at the example of the magnification factor of these pictures is 2. .</ P> <P align=center> </ P> <P> 100% quality compressed JPEG image is difficult to distinguish between the original image, but the original JPEG image file size is only 1 / 6. .</ P> <P align=center> </ P> <P> 80% quality compressed JPEG image quality is still good (remember, after twice the figure is the enlarged image), and its file size is only .the original file to 1 / 10. .Please note that the yellow crayon in the edge of the screen a bit fuzzy fade. .Most digital cameras to provide users the option to JPEG compression level, of which "the highest-quality JPEG" quality level is often higher than 80%. .</ P> <P align=center> </ P> <P> 60% quality compressed JPEG images. .If the reader to look carefully, you will find JPEG compression between the regional and unnatural "hair-like" compression marks. .While the quality decreased, but 60% of the quality of the JPEG compression has been used for the page is enough. .Its size is the original file size of 1 / 20. .</ P> <P align=center> </ P> <P> 10% quality compressed JPEG images, JPEG compression area is clearly visible, image quality decreased significantly. .This low-quality JPEG images only use is to allow us to understand principles of JPEG compression (high quality JPEG compression is difficult to see the area), and of course we would not normally compress the image so powerful. .</ P> <P> practical tips </ P> <P> <1> we edit images, it is best to "middle image" (for example, TIFF, PSP and PSD, etc.) stored for later .use. .If you save an image directly to the JPEG format, and then the file is closed, then open to the same compression quality setting the image then save the image does not become a ... ... a small, but the image quality will decline further. .Therefore, we should be processing the image, fishes pictures to be compressed. .</ P> <P> <2> Digital cameras usually have quality JPEG compression options, such as fine, medium, basic ... ... unless you shoot with RAW or TIFF format, or use the best quality setting. .Some digital cameras, even if choosing the best quality compression, it is still very high degree of image compression. .</ P> <P> Reference: <U> RAW image format </ U> <U> TIFF image format.