Color Heatmaps

Generate a cosine distance heatmap based on CIELAB color space.

How to use:

1. Select a picture from the drop down menu;
2. Draw a polygon with your mouse: hold left mouse button down to draw, release when finished;
3. Wait while it computes the similarity heatmap. Computation is asynchronous, so doesn’t freeze the browser;
4. Win win win.

Some specifics:

• The histogram is generated based on multiplying the A & B channels from CIELAB.
• CIELAB has two color description channels, compared to HSV’s single color channel. I’m hoping two channels gives a “wider” distribution - while still remaining reasonably invariant to luminosity.
• The distance metric is cosine (i.e., inner product between histograms).
• A sliding window approach is used to generate local histograms describing the surroundings of each pixels. At the time of writing this is 9 by 9 pixels, with the current pixel as center. Pixels are repeated at edges to avoid out-of-bound issues.
• The histogram, at time of writing, has 100 buckets.

The paintings are from WikiArt and the photos from VGG.