Is it Better to Upload 1024 px or 2048 px Images to Second Life?

In Second Life, the avatar Hermes Kondor raised some questions about whether it is better to use 1024 px resolution images or 2048 px images. Uploading both types of images is permitted, but Hermes had noted that when he uploaded a 2048 px image, then saved that same image from SL back to his computer, the image was always returned in 1024 px format.

This experiment used used test files (available below) to examine the differences between 1024 and 2048 px images when they are uploaded to SL, and how they are displayed. In the first graphic, you can see how small the test area was on a 1024 px image.

For the samples titled, "As viewed on SL" all graphics were set to the highest possible levels with the exception of draw distance, which was at 256m. Resetting the draw distance to 32m to exclude competing images, did not improve the resolution.

The test files for this experiment are appended below, and I would encourage others to try the same experiment to see if the results are consistent. Please contact Rob Fossett in SL, or the webmaster via email with your results.

This test was conducted on August 13th, 2023. Results may change if SL decides to upgrade display resolutions and/or the algorithms used to produce the display images.

Conclusions:

1. 1024 px images display better than 2048 px images on SL, but the resolution compared to the original image is very poor in both instances. This is likely due to the compression algorithms SL is using to descrease file sizes and present graphics more quickly.

2. Part of the compression algorithm involves anti-aliasing, as demonstrated in the averaging of the four adjacent colors in the colored section of the test patch.

3. The images viewed in Second life do not show clear pixel delineations, so this may also be the effect of one's personal computer system and its processing of images as they are greatly enlarged. In my case I am using a Samsung 4K monitor and AMD Ryzen 7 5700G with a dedicated NVIDIA RTX 3060 graphics card, and the returned images are screen captures of the highly magnified image.

4. Given the limitations to resolution in Second LIfe at this time, it is better to prepare graphics in a 1024px format for use in SL.

Note added later in Discord:

When we create graphics, an individual pixel can only be one color. When I zoom in on any image in SL right down to the level where I should be able to see individual pixels, I don't see pixel-sized blocks of color. Instead, I see gradients across my screen that can roughly show the former location of the pixels, but they are blended into each other. It must be that, as we zoom in on an object in SL, some averaging takes place, like anti-aliasing. Usually, if I have lines in my graphics that are too harsh and block like, I will touch them with a smoothing brush to average things out. Now I wonder if that is necessary or if SL will do that anyway when the image is presented.

(A partial answer is in the next test, linked below.)