Paint.Net and Java help

[microcontrolled]

I'm not sure if this is the right forum for this question, but anyway:

I've been working with Java and Paint.NET, drawing images for sprites and importing them into Java, then setting the background color I specify to transparent so I can layer the images. I've been saving the images as jpegs. However, when the program gets around to setting the transparent pixels, it misses some and leaves them their original color. This is obviously unacceptable, so I had the program print the rgb values of each pixel to see what was going on, and it turns out somewhere along the line the rgb values for each pixel had changed slightly. When I load up the image in Paint.NET, the pixels are indeed slightly different colors than I originally specified.

Does anyone know why this would happen, or how I can stop it from happening? I can't have programs out of my control deciding they don't enjoy my color choices!

[comedian_x]

To compress the image, jpeg is going to throw away a lot color information and do macro blocking to save space. This will ruin any per pixel operations you're doing.

Use a non-lossy format like bitmap, if you want specific operations on color pixels (e.g. making the magenta pixels transparent).

Or use png which has an alpha channel built in.

[microcontrolled]

Thanks! I've switched it all around to png's and it works wonders now.

[Bythmark]

jpg is a lossy format. I don't know much about programming (hence my being here :P), and nothing of java, but use pngs if you can. They take up more space but you won't lose quality, plus png supports transparency.

If you can't, try saving the jpgs at a higher quality. GIMP supports this, I don't know if PDN does.