how can be the pixels value of an image files and text files got for compression?

Answer 1

Basically, how does compression work. It is build on the fact that there is usually some structure in files. The first byte would in a graphic file would be specified as a single bit, then every other byte in the file is stored as a difference from that bit. In that way you can reduce some of the space used in the file and get compression.

The other way that graphic files are compresses is to use an index into a color table (the index is smaller) rather than use the actual colors. This is sort of like use paint by number to represent a painting rather than the original (gif and png can use this technique)

The third option is to reduce the number of colors in the picture and make an approximation of the original image. jpg does this so that not all of the possible colors are added to the graphic

Answer 2

Usually, the program will read in the image from the source, loading the compressed image into memory. Then, decoding the compressed image in memory, then, for instance, draw the image to the screen.

Answer 3

Some pictures are bigger than others. And some pictures have more colors than others. Go to http://www.spinwave.com/crunchers.html
to make a gif or jpg smaller by reducing the number of colors.

Answer 4

how about a little more information? what language are you using? what kind of image?

Answer 5

if you are in the process of learning english then thats okay, but if english is your only language then i consider you illiterate. youy question is to incoherent to answer. in other words, it doesn't make sense.