I have anti-graffiti surface samples sprayed with graffiti spray. I am going to measure intensity changes in color of surface. How can I quantify them?
Bahareh, can you explain what you mean by intensity changes? Changes between what, for example between the original surface and its state after removal of the graffiti?
Detlef Ruschin I want to spray graffiti color on the surface and after washing with water, I am going to quantify that how much of color still remains on the surface?
That's what I thought. An easy, but probably not so well suited, method is to make photos before and after and to compare the color values at a couple of selected places (use average difference). Many photo editors have "color pickers" that you can use to reveal the color values of selected points, usually given in terms of the three value R, G and B.
The problems with that approach are that 1) a camera is no reliable measurement device and 2) one does not know which RGB difference is ok and which is unacceptable.
The correct approach would be the following. You need to obtain a "spot color meter" (google that) and make the before/after measurements with that. The color values provided by a color meter are called X, Y and Z. The measured XYZ differences must then be fed into a formula that tells you, how large the difference appears to the human eye. The best and standardized formula for that is CIEDE2000. You could use an older formula, though, called CIELAB ΔE, the calculation of which might already be built into the color meter or an accompanying software.
Detlef Ruschin Thanks so much. It is possible to check this color changes in Image J?
Unfortunately not, because image colors are not identical to the real ones, and the exact relationship changes from one camera to the other. You could use images to make rankings between different protective coatings, because larger color differences in the images will correspond to larger differences in reality.
- Badges
- Science topic
- Similar topics
- Social Psychology
- Attitude