My vintage red fabric collection got the COLOURlovers treatment — thanks evad! I knew about this site previously, and thought they just pulled palettes out of inspiring images, but the inspiration and usefulness doesn’t end there. First, you can click on the palette, rank it, favorite it if you’re a member, download the palette image itself and/or the color information for use in a number of design tools. The palette page shows each color individually with its HEX and RGB codes too.
See down there in the lower right? You can also generate user-submitted patterns using your chosen palette. I used my red tree fabric to create the pattern in the screenshot below. Here’s another one I made from this fabric’s palette. It doesn’t seem like you can do much with the generated patterns (e.g. download a high-resolution version to use for Spoonflower, for instance?) … but I’ll have to check more into that.