Today’s Question: I would hasten to add that when using a Curves Layer to adjust tonality without wishing to affect color, it is best to use the Luminosity blend mode.
Tim’s Quick Answer: Yes, if you add a Curves adjustment layer to an image in Photoshop, you can change the blend mode to Luminosity to ensure the adjustment will only impact overall tonality for the image, without any impact on color.
More Detail: While today’s question isn’t exactly a question, it is a follow-up to the question I answered on May 6th related to the behavior of the Channels adjustment layer in Photoshop.
By default, all adjustment layers have their blend mode set to “Normal”, which means the adjustment layer simply applies to underlying pixels based on the behavior of that adjustment layer. There is the potential, however, for there to be a relatively minor unintended impact on other attributes, especially with somewhat complex adjustments such as Curves.
In particular, there is a risk that when applying a tonal adjustment with a Curves adjustment layer that the color may be impacted in the image more than you would like. If you want to restrict the Curves adjustment layer to only affect tonality and not color, you can change the blend mode for the Curves adjustment layer to Luminosity using the popup at the top-left of the Layers panel.
The same concept could apply in other situations. For example, if you want to use an adjustment layer to affect color without impacting tonality, you could change the blend mode for that adjustment layer to Color.
In the vast majority of cases the impact of using the Normal blend mode for an adjustment layer rather than, for example, Luminosity or Color, is going to be quite minimal. However, if you want to exercise maximum control over your photos with no other unintended changes, changing the blend mode for an adjustment layer can be helpful. Just keep in mind that this will also limit the effect of an adjustment layer. For example, with a Curves adjustment layer if you set the blend mode to Luminosity and then alter the curve for the Red, Green, or Blue channel, you’ll only be impacting the overall brightness of the image with no shift in color balance.
You can read the question and answer that today’s question was a follow-up to on the Ask Tim Grey blog here:
https://asktimgrey.com/2026/05/06/curves-behavior-with-channels/
