Dear Rei Vilo,
thanks for your answer. I didn't reply because I didn't see the answer.
So I succeed to download an image in the kentec K35. But I have a problem with some computers: with the computer in my office, it works fine but with some computers from another labs, there is a problem of quality of the image. On the following first image, the quality is good.
The following image have some white lines between each pixel and the color are not respected.
It's the same code that is used in the two cases.
Do you have an idea of the problem ?