I use a site called photopea. I usually pick a bay horse or a black horse when I do darker horses, and I tend to pick chestnut, white, or palomino when doing lighter horses. Picking stock that goes better with the horse on HEE makes things MUCH easier.
For example. If you were to do an apricot color change, I would recommend using chestnut horse stock to begin with. With a grullo color change, I would recommend using black or bay stock to begin with.
Another method I use is grayscaling. Now I don't know how your site works but on mine you would desaturate the horse completely and select the horse, then you would click 'add new layer' and set it to overlay. After that, you would select the base color of the horse on HEE and paint it on that overlay layer.
Hope this helped a lil. I'm half asleep so excuse anything that may not make sense <3 xD
Crisp, Clear, and Cool
