I enjoy bringing one of my sketches into a painting program to transform it into a painting. Here I used Paintstorm Studio Pro to apply watercolor to a sketch. To get a good result, I first prepared the photographed sketch in iColorama, and then when I was finished painting in Paintstorm, I again brought the image into iColorama to finish it. I find iColorama's tools for editing tone and color to be much easier to use than those in most painting apps.
I made this 90 second sketch of a live model using a Tombo pen on paper. Then I took a photo of it with my iPhone.
I opened the photo in iColorama. I used Form/Unperspec to correct the perspective. I used Style/Flow to smooth the lines, and I used Adjust /Levels to darken the lines. I used Effect/Denoise preset 4 to de-alias the lines, which is sometimes needed after using Flow, and I used Effect/Sharpen at low radius to add some sharpness, which is sometimes needed after Denoise. When sharpening this image, I was careful not to introduce halos (by trying different slider settings), which can be particularly visible in this sort of image.
I opened the image in Paintstorm Studio Pro and on a new layer, I used the watercolor brush. It is a tricky brush to use and seems a bit unpredictable, but gives a lush, beautiful watercolor feel.
On a new layer, I used the classic transparency brush to paint shadows. Then I blurred the layer to soften the shadows.
Because the paint layers had partially obscured the sketch lines, I made a duplicate of the sketch layer and dragged it to the top of the layer stack. I changed the blending mode of the duplicate sketch layer to Multiply mode so that the sketch lines cover the paint in the lower layers, but the white areas don't obscure the lower layers. I saved to my camera roll.
I opened the image in iColorama and used Adjust/Levels to lighten the fur stole.
I used Texture to add a gray texture as a sort of shadow, and used a brush mask with a big soft brush to apply the shadow just to the blank areas at the bottom of the image, in a way that fades nicely into the white background above it.
I used iColorama's Txtcurve feature to add a line of text, curved to match the curve of the figure. (See my tutorial for how to use Txtcurve here.)