Colour Wheel

Having, hopefully, taken sufficient images to have a reasonable chance of creating a colour wheel I was concerned about trying to compare the image on the screen with the colour wheel in the Course material. Printed colours are reflected light off the page whilst what we see on the screen is transmitted light making comparison difficult.

Initially I thought of scanning the page into Photoshop and whilst this seemed to provide a satisfactory result I could not be sure that the scanner did not have a built in colour bias. I gave the problem further thought and decided that I would photograph the page with a gretagmacbeth colorchecker adjacent to it and in the picture. I was then able to use the eyedroppers in Curves to test the appropriate colour patches on the chart and adjust the image. The result produced an accurate image (colour wise) of the printed colour wheel.

To make as sure as I could be I carried out the same process but this time used a swatch card that had a patch "camera raw white balance". Comparison of the two results showed that they were very close to each other in terms of the colours.

Satisfied that the image that I had obtained was accurate I then used the Eyedropper tool in Photoshop to sample the individual colours using a 101 x 101 pixel average. ( the usual 3 x 3 or 5 x 5 pixel average gave some differences as I moved the tool over the colour image). I noted the RGB values in the Info palette and then created individual colour patches using these values.

Okay that was the technical bit now all I have to do is carry out the comparisons.

I may be gone some time!