## Friday, July 13, 2018

### The Painter - Blade Runner

I am going to use "The Painter" to simulate digital painting. The input photo is from the movie "Blade Runner", the original, of course.

Original photograph we are gonna turn into a digital painting.

Input to the "The Painter":

brush radius, opacity strength, and bumpity strength = 64 0.5 1.0 32 0.5 1.0 16 0.5 1.0 8 0.5 1.0 4 0.5 1.0 2 0.5 1.0
f_sigma = 0.1
error_threshold = 60
canvas rgb image = canvas_rgb_image.png
canvas bumpity image = canvas_bumpity_image.png

The two values after each brush radius are the opacity strength and the bumpity strength. The bumpity strength is not a factor in digital painting since there is no height associated with the paint. In digital painting, you usually want the colors to blend together so a value of 0.5 for the opacity is chosen (initially). Depending on the size of the input photo, you may want to get rid of the smaller brushes right off the bat. The larger the input photo, the less you want the smaller brushes to be included (unless you dramatically reduce their associated opacity).

Resulting painting:

Painting 1.

I really don't like Deckard's rendering as it is way too coarse. Also, the small paint brushes left smidgens of paint on Rachel's face, which doesn't look good. Let's get rid of the small brushes (radius 4 and 2) and make the rendered painting finer by decreasing error_threshold (from 60.0 to 20.0). Hopefully, we will get a better render of Deckard's face. We'll worry about Rachel later. Note that instead of getting rid of the smaller brushes, I could have decreased their opacity (use an opacity of 0.1 instead of 0.5).

Input to "The Painter":

brush radius, opacity strength, and bumpity strength = 64 0.5 1.0 32 0.5 1.0 16 0.5 1.0 8 0.5 1.0
f_sigma = 0.1
error_threshold = 20
canvas rgb image = canvas_rgb_image.png
canvas bumpity image = canvas_bumpity_image.png

Resulting painting:

Painting 2.

I like Deckard's rendering but I think Rachel's could be a little bit coarser. Let's raise error_threshold from 20.0 to 30.0 leaving the brushes alone.

Input to "The Painter":

brush radius, opacity strength, and bumpity strength = 64 0.5 1.0 32 0.5 1.0 16 0.5 1.0 8 0.5 1.0
f_sigma = 0.1
error_threshold = 30
canvas rgb image = canvas_rgb_image.png
canvas bumpity image = canvas_bumpity_image.png

Resulting painting:

Painting 3.

Now, I like Rachel's rendering but I think Deckard's rendering is too coarse. This happens often but there is an easy solution: simply combine the two paintings into one. How do you do that? In Gimp, you load the two paintings as layers, turn on layer transparency (click on "Layer", "Transparency", and "Add Alpha Channel"), erase what you don't like on the top layer with a soft brush, and export the result.

This a combo of painting 2 and painting 3 (I put painting 3 on top of painting 2 and erased Deckard's face to reveal the one underneath):

Combo painting 2 and painting 3.

Just for giggles, this a combo of painting 1 and painting 2 (I put painting 1 on top of painting 2 and erased Deckard's face to reveal the one underneath):

Combo painting 1 and painting 2.

Personally, I like the coarser look on Rachel better (although I should have removed or muted those small brushes) but it's really a matter of taste.