Somewhat similar to the Digital Colour Meter (or Color Meter depending on computer language settings) that comes with Mac OS, with extra info.

Info extra to a basic digital colour meter includes

1. the pixel colour in Hue, Saturation, Value (HSV) notation in addition to RGB. HSV is rounded to integers for reasons of space in the panel.

2. the pixel brightness, by specified brightness calculation criteria. An integer betwen 0–255 which equates to a greyscale value for the pixel.

3. the row and column within the image where the pixel is located.

4. the pixel opacity, i.e. the A part of the RGBA value expressed as an integer percentage.

5. the colour name, calculated from its HSV values.

I wrote this page mainly for diagnostic purposes when debugging other scripts but find it useful for looking things up too. Gives some useful info beyond the Mac Colour Meter, plus of course will run on any platform that hosts web pages, you don’t have to have a Mac.