Thanks for replies!
dxw00d, I'm trying to make instant camera with my thermal printer.
So my plan was re-read SPI RAM and write data to thermal printer.
AWOL, thanks, I see it is not feasible to decode JPEG file with Arduino instantly...
So.... I think now there are two ways to do this.
First way is getting new camera which gives data pixel by pixel, and it should not be too fast.
Maybe CMOS cameras can do this? I don't know please let me know how CMOS camera works.
Second way is to just forget about Arduino things and do it with other ARM things.
But I cannot do that! HOW SAD!