Project 6: measuring colour

I was directed to make a duplicate print of my personal colour chart and scribe the RGB and HSB values onto it.



Personal Chart showing HSB and RGB values

Typing all these values on was time consuming but it does mean I have a permanent record stored electronically, it also reminded me that to get the ° symbol all I had to do was Alt+0176... handy to know!

Taking three photographs, one to contain neutrals, one skin tones and the final to have vegetation I had to measure and note down the values of the important colours and compare them to the OCA chart and my own personal colour chart.

I began with looking at the skin tones in a portarit of my son...he loves me using his images ;o)




Portrait for checking skin tones

A few issues to begin with as he doesn't have a uniform skin tone, quite an olive complexion on the whole, he does have a healthy pink glow therefore readings were different depending which area I sampled....I chose an area at random and then compared the results. My image was quite close to the OCA chart, on my personal chart they were not taken from actual skin but even so the difference is fairly minimal. Quite pleased with that ;o) Means I got the skin tone fairly accurate!

Comparing Charts



 

Values	Photograph	OCA Chart	Personal Chart
H	15°	20°	11°
S	22%	25%	28%
B	91%	95%	92%
R	231	241	234
G	193	200	180
B	180	180	168

Secondly I looked at the image containing vegetation.



Quite a few of my vegetation shots I had previously used to compile my personal chart therefore thought it would be pointless comparing them as they would have the same values. Instead I chose this tulip shot which had a variety of greens in the stem and background, although not vegetation I thought I'd compare the red too.



Comparing Charts

By eye once again the colours do not appear that dissimilar and the values are fairly close too. The darker greens in the background when sampled were very dark and didn't really match anything on either chart.



Values	Photograph			OCA Chart			Personal Chart
	LG	DG	R	LG	DG	R	LG	DG	R
H	64°	64°	3°	64°	69°		64°	63°	3°
S	100%	99%	99%	93%	63%		76%	84%	98%
B	40%	42%	99%	84%	43%		82%	43%	84%
R	96	100	253	201	100		198	104	213
G	103	107	15	215	110		208	109	15
B	0	1	2	16	41		49	17	4


Finally the neutrals were sampled for a street image taken on the Commercial Road in London



Image to check neutrals

There were not many neutral tones on my personal chart, the only one that I could attempt to match was black.



Comparing Charts

From the values sampled you can tell that my neutrals aren't really neutrals at all. I guess that would be due to a mixture of colour cast and also some of the surfaces could be reflecting other colours. Quite a few areas on the grey road were also made of  different tarmac, some appearing to have a pink mix....



In my photographs the black has a very high saturation but the other neutral tones are close to zero, being 9,4 and 1. RGB levels aren't equal but are quite close. Not sure now what the settings of my camera were it could be I had the incorrect WB set at the time, although not neutral I was surprisingly pleased at how acceptable they were.



Values	Photograph				OCA Chart				P/C
	1	2	3	4	1	2	3	4	1
H	252°	60°	103°	60°	0°	0°	0°	0°	266°
S	136%	9%	4%	1%	0%	0%	0%	0%	44%
B	5%	51%	70%	98%	0%	50%	75%	0%	6%
R	10	129	174	249	0	128	191	255	12
G	19	129	179	249	0	128	191	255	9
B	14	117	172	247	0	128	191	255	16



Once again this exercise has shown how important it is to understand colour cast and noting which areas of an image should be neutral so post processing can be done as accurately as possible. Although pleased that my images are not as far out as I thought they might have been, I can see there is room for improvement.