Various formats to describe the storage of an image file such as:. Bmp; .tif; .pcx; .gif; Both .gif and .jpg (or .jpeg) formats are most widely used due to their good image compression capabilities, and .bmp files are generally larger in size than .jpg. with .jpeg.
There are many methods of image compression, but they are based on the principle of finding "superfluous" in the data and encoding them in different degrees. A relatively efficient image compression technology can work with large, multi-color images, which are JPEGs, the abbreviation for the Joint Photographic Experts Group. This technique can achieve compression ratios more than eighty times that of the original image. However, the higher the compression ratio, the more unstable the image will be, the closer it is to the original image than the original image. Anyway, with the naked eye it is hard to see the difference.
The principle of the JPEG compression method is: Cut the image into small cubes, analyze all the color data, the brightness that the blocks contain by the matrix equation. Color images in RGB (Red, Green, Blue) are converted to YUV. While human vision is very sensitive to the Y system, it is less sensitive to U, V. The system will compress the Y component of the image to a much lesser extent than U and V. Next, Discrete cosine transform, followed by Hoffman coding. When decompressing images, the execution steps will reverse the above process.
As stated, JPEG compression technology will lose information at decompression, the higher the compression ratio, the more information it takes to extract. So to solve this problem, December 1999 & nbsp; a draft standard for image compression using the new JPEG2000 technology. In August 2000, a draft of the JPEG2000 standard was circulated among photo professionals. It was subsequently endorsed as an international standard in December 2000, and was ISO-certified this year to allow applications to be distributed and distributed.
With JPEG2000 the image processing technique will achieve spectacular results as it can compress from 100-200 times that the image is not flawed compared to the original image. But what is the difference between the JPEG2000 and the JPEG2000?
JPEG2000 is an image encoding system that compresses techniques based on shortwave techniques. Is a mathematical utility that allows the description by a simple formula what happens at a precise time of the signal. With a short wave sequence, only represent a few formulas, irregular lines that do not need to describe the characteristics of each point one. And of course, it will be very useful when analyzing a digital image file.
The algorithm in JPEG2000 technique is to select a small number of shortwave waves that are repeated in different places, different rates have accurately depicted the signal of the image. Compressed image does not contain more than the number of position and expansion of each short wave. And the block-based, region-by-sector (ROI-Region Of Interest) technique is also a significant advance in the JPEG2000 encoding algorithm.
Accredited by the ISO also means that in the near future JPEG2000 will be commercialized through the digital industry whose best interests are the remote imaging diagnostics in Medicine, the image above Internet, maybe even digital movies through Motion JPEG2000 format. Sure, mobile devices such as handheld computers and mobile phones will not ignore this image compression standard.
You are a digital photo enthusiast who can refer to the following address:
http://www.jpeg.org
http://jj2000.epfl.ch
http://ltswww.epfl.ch/~eurostill
http://spear.jpeg.org
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Some application software of JPEG 2000
1. Morgan JPEG 2000 ToolBox V2
Usage is very simple, just run the program, select the picture format conversion needs. Save as, save location and name the new file. The JPEG2000 Setting box allows users to set up lossless compression options. And most importantly, apply the ROI (Regional Of Interest) technique to use the mouse to mark the area in the image you want to achieve higher quality than the rest.
Download the trial version from the address http://www.morgan-multimedia.com/
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2. Lead Tools JPEG2000
6.47MB 60-day trial, similar to the use of the software Morgan JPEG2000.
