Well, that is because RedBubble, like any other print-on-demand site, uses CMYK printing for their shirts. When you upload an image, the preview is automatically converted to CMYK to give the customer a more accurate idea of the final product (tho the preview’s conversion usually doesn’t match up with the printed result, so it is flawed in that case).
Other POD sites don’t do this and it leaves a lot of people wondering why their print came out “dull” when it’s simply a result of the printing method, as CMYK cannot produce vibrant neon colors because it’s
color, not additive. Though I have been very impressed with the quality of DBH!
Screen printing and dye sublimation (so, all-over prints) are the only garment printing methods that produce those really bright colors.
Also sorry if that’s totally not what you were getting at but I thought I should mention all this to my followers because it’s not often understood!