Resolution, compression, and PPi

[Stefan A]

Hello

Although I am not new to digital cameras, I am new to the S2IS which I just recently purchased. I don't understand how resolution, compression, and ppi relate to each other. I have been taking some shots at different resolutions and compressions and have noticed that when I open the picture in Paint Shop Pro, and click image info, the PPI is always the same no matter what. I am under the impression that I need to take pictures at 200-300 ppi in order to print acceptable prints. How can I take a picture at a higher ppi?

Stefan

[adas]

Welcome to the forum, Stefan. The ppi (pixel per inch) is only important when printing. 180 ppi is about the minimum pixel density on the paper. If you print below that, the pixels begin to grow in size and the eye will notice them on the paper. 300ppi is a bit high, used only if you currently watch the pictures very close, sometimes with magnifier. It's your choice here.
The compression level allows you to save card space by choosing a highest compression, but also the image quality begin to drop. Again, it's your choice.
There is no direct relation between resolution and compression.

[Stefan A]

Thanks

When I take the picture, should I be able to set the ppi? Or do I just change the 72 to 200 (or whatever) in the resize option?

Stefan

[RossW]

Maybe an amplification of what adas said: you don't specify the ppi in the camera... it will always be 72 dpi for the S2. It's the printing process that handles getting the correct density for a decent image on paper. You don't have to resample it (change ppi) when printing, just specify the overall size of the print. (Although perhaps some software approaches this differently.)

Resolution in photographic terms refers to the size of the image in pixels (e.g. 1024 x 768, etc.). Compression manipulates the data to throw away some bits for smaller size files. Up to a point, this won't noticeably degrade the image, but it can be pushed too far and then there will be visible artifacts. As adas says, no direct relation between resolution and compression, other than too little of one and too much of the other spells trouble.