Selective color (color splash) on an image
Keep only one color in color and turn the rest of the photo into black and white, for a "color splash" effect that highlights a specific detail. Choose the color to preserve and adjust the accepted hue tolerance.
How it works
Each pixel is converted to hue, saturation and lightness (HSL). If its hue is close enough to the chosen color (according to the tolerance in degrees) and its saturation is significant, the pixel keeps its original colors. Otherwise, it is replaced by its grayscale equivalent, creating the characteristic contrast of color splash.
Why do some gray or pastel areas never go back to color?
Highly desaturated colors (close to gray) have no reliable hue to compare: they are therefore always converted to grayscale, even if their theoretical hue is close to the targeted color, to avoid an inconsistent rendering.
How do I broaden the area kept in color?
Increase the hue tolerance: at 90°, a wide range of colors close to the chosen hue will be preserved. Reduce it to keep only a very specific color, for example only the red of a specific object.
Hue analysis and grayscale conversion run entirely in your browser: your photo is never sent to a server.