Doug Stockdale's Singular Images

September 18, 2014

My RGB to Grayscale Conversion process

Filed under: Memory pods, Photography — Tags: , , , — Doug Stockdale @ 4:55 am

028B 06-03-14_Memory_pods_162638_Grayscale_No Memory pods

#28 No Memory (Pods) copyright 2014 Douglas Stockdale

I had mentioned in an earlier post today that when I converted my color photographs (RGB) in Photoshop to a Grayscale (Black & White) image that I first had to flatten the layers of the color image. I received a question from a buddy as to why I did that?

I now realize that there are aspects of my work flow that I have taken for granted, such that it is generally recommended that for image sharpening (unsharp mask) and adding a curves adjustment layer, that you should consider changing the layer blend setting from Normal to a Luminosity setting.

As to why, I had to go back to my Scott Kelby book “The Photoshop CS book for Digital Photographers” published way back in 2003. My goodness that makes me feel a bit dated. Okay, so Kelby states that for image sharpening of color photographs (RGB mode), I do not want to sharpen the color data (normal layer blend mode), but just the luminosity data (Luminosity layer blend mode). By adjusting just the luminosity I preserve the hue and saturation of the base image, otherwise these will shift.

What I do notice is that if I sharpen the color data this can create some  halo effects within the image, but that does not occur when I am using a luminosity blending layer. When I add an adjustment layer like a curves to change the image contrast, if in the normal layer setting, I will also be changing the color data and besides changing contrast I will also alter the color (hue & saturation) of the image. To eliminate the color shift I adjust only the luminosity layer.

The kicker is that in Grayscale the Luminosity layer blend mode is not an option since a black and white image has neither hue or saturation. So when I am changing the mode from RGB color to Grayscale Black & White, the adjustment layers I use for the RGB color creates a conflict in Photoshop for the conversion. A dialog box pops up and asks to eliminate these adjustment layers, so instead I proactively flatten and eliminate the layers prior to making the mode change from RGB to Grayscale.

As to the photograph in this post it is an image that pushes my artistic boundaries as I rarely work with such dark images. Nevertheless I do find it fitting and appropriate for the feelings I am investigating in this case; how might one feel if they did not have the ability to remember their past? Everything is a blank; words, the meaning of words, associations and the life and history of your friends and family, essentially everything about who they were.

Best regards

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