Show bar chart of colors in sample images

Display the distribution of colors in the sample image(s) in a bar chart.
Potential packages to do this are [colordistance](https://github.com/Imageomics/genotype-phenotype/issues/8) (R package, so likely would require translation, used by the butterfly group). May also be able to use [phenopype](https://github.com/phenopype/phenopype) (python package, not currently used by butterfly group, but potential).