"A Day in the Park"
We are all familiar with black and white images which contain luminosity data and no colour data. The image above is the converse of that; it contains colour data but no luminosity data.

Most photo-editors contain easy-to-use tools to to create b&w images by removing the colour data, but few of them have easy-to-use tools for removing the luminosity data. I use GIMP to do this because it contains tools for using the HSV (Hue-Saturation-Value) colour model in which the “Value” (V) is a measure of luminosity. Setting V to its maximum effectively overwrites the original luminosity data leaving just the colour (hue and saturation).

Typically, most of the detail in the original image is in the luminosity data. This detail is
completely gone from the colour-only image, creating a ghostly effect in many cases. It leaves a lot to be filled in by the imagination of the viewer.

I have been using this technique for about fifteen years now. The images need careful selection, but I really enjoy some of the results. They are often very impressionistic and much brighter than the original photos.

The original photo for the image above was taken with a Panasonic GM1, 21mm lens at f/5.6, 1/400s, ISO 200, processed in Lightroom and GIMP.