I want to share an image that most accurately represents the color and shade of a dress*. I have an 18% gray card that I can use to set white balance, but I want to know if there is an ‘ideal exposure’ that can be set using it as well. What ‘should’ the RGB values be for 18% gray?
*My daughter ordered it online and it is very different than the one on the website (yes I know, calibrated screen etc…). She wants to send an image to the company showing how off it is.
According to CIPA and ISO, 118/255, 118/255, 118/255 in sRGB color space, card illuminated by Daylight D55 per ISO 7589.
http://kronometric.org/phot/std/DC-004_EN.pdf
That value of middle gray is the basis for the ISO definition called ‘Standard Output Sensitivity’
Another common definition is a lightness of 50 in CIELAB color model which gives you 119 in sRGB.
See here if for some reason you don’t work in sRGB.
http://www.brucelindbloom.com/index.html?ColorCalculator.html
As to the image, not as simple as it sounds.
I recommend to shoot the dress under lighting where she will wear it but with your gray card included on top of the material. Then open the image in an editor set to sRGB Working Space and click on the gray card to set the color balance for the dress. Don’t mess with anything else. Save the image as a JPEG 100% Quality but full sub-sampling (4:2:0, 2x2). Cropping is OK.
P.S. Make sure that the JPEG has an embedded sRGB color profile.
Good luck …
What is the purpose of changing the working color space to sRGB?
To avoid any color management confusion since that would be the preferred output color profile, due to the Original Poster having probably no idea what Image Viewing equipment the garment Vendor uses.
How did that go?
She attempted to get the refund without sending an image, it is just something we wanted in our back pocket. I’ll have to ask her what happened.
Thanks for the help.
She ended up getting store credit. Picture wasn’t needed.
Shouldn’t that be the job of setting the output color profile?
Of course, but I had no idea how the OP works.