Source file for textures: recommended resolution

I realize this may be a dumb newbie question, but I've searched and just can't find the answer.

I see much discussion on dimension and ratio of source images; what I am not sure of is, when you create your 512x512 (or whatever) source image file, what resolution should be used.

Should I assume 72 pixels per inch, since it's being displayed on a web browser? If I use a different resolution for higher detail while I work, will that matter? I believe the image dimensions "shrink" in size if you start at 200 pixels per inch and then downsample it to 72 prior to uploading (or if it is automatically downsampled as part of the SL jpg conversion), so I imagine this could be a problem.

So, recommendations on resolution to use would be appreciated.

Thanks!

Any 'pixels per inch' resolution is totally ignored, so it doesn't matter. All that matters is the actual number of pixels. Use the smallest size you can without losing detail.

Ppi and dpi are mostly only meant for print media and has no meaning within SL. Just work with absolute pixel dimensions.

My rule of thumb is, 512 pixels for large items like walls and floors. 256 pixels for avatar sized objects like doors, pots, etc. and 128 pixels for much smaller stuff thats about half the size of a regular avatar.

Dimensions don't need to be square. For long and thin signages, you can use 1024 x 256 for example.

For your source images, keep them in relatively high sizes for later use. Only downsample and crop when you want to upload them to SL.

Also, while Photoshop does a decent job of downsampling, there are other apps like XnView that gives you more downsampling options to tweak things.

The "pixels per inch" value in your graphics program is meaningless for anything other than printed output. A Photoshop file set to 72 ppi for a 2048 x 2048 pixel image creates exactly the same .tga file that a Photoshop file set to 2048 ppi for a 2048 x 2048 pixel image creates. In both cases, the image has just so many pixels, and SL doesn't read the ppi print resolution info.

I find it useful to design textures at double the size that I intend to output them at. Then, just befoe I save as a .tga file to import to SL, I scale the image down in Photoshop to the smaller size. So for example, to make a 512 x 512 clothing texture, I design it at 1024 x 1024 pixels (and 72 ppi, though that doesn't matter). Then I select 'image size' in Photoshop and set the image size to 512 x 512 and 72 ppi prior to doing a 'save as' to make the .tga file.

The one advantage to working at a specific ppi size is that everything is the same size proportionately when you are building the image. For example, consider the confusion that might occur if you used part of a digital camera pic at 300 ppi and were pasting it into a texture file at 72 ppi. The pasted in part suddenly appears 4x larger. So I set all my source images to 72 ppi (allowing them to re-scale the print size so I don't lose any pixels) before I start working with them.