Does photoshop do some dithering in the gradient? Thats the way to get smooth gradients from 8bit images, but as antokhio says, check your format, as if your outputting 32bit it might be getting truncated too. Its perfectly possible its different, I’ve never done a comparison!
From your images it looks like the gamma is different, again this could be photoshop color managing, as well as the banding looking different…
Not sure what quality you get (might be gfx card dependent) but you can try a gradient with different vertex colors on a surface with either one of the basic .fx that already does vertex color lerping or make your own…
you guys completely miss the key difference here: photoshop uses bicubic interpolation while vvvv and videocards in general using linear interpolation. there are plenty of articles/docs out there using google how to do bicubic interpolation in C which after some mangling easily translatable to hlsl
a bicubic interpolation ships ships with vvvv since 2008, just have a look into the nodebrowser. but that would only change the curve between black and white. dithering is also important here i’d say.