We are often asked why we need to understand Layers & Masks in Photoshop? After all, we can always blend or adjust images using HDR software, right? Here’s a quick explanation.
Take a look at the images above. Notice that the highlights in the image on the left (Image 1) are overexposed. You can’t see any detail in the white areas in the water. On the other hand the Image 2 is processed for the highlight and the shadows and midtones are under exposed. In the final image (Image 3), I corrected the exposure using Photoshop Layers and Masks. I can create a similar blend using an automated HDR tool.
But this is not a finished image. I want to take it further. I think the image needs some corrections to improve the contrast in the rocks, and to help focus the viewers attention on the water itself. To accomplish this, I used different layers and masks to limit each adjustments to a specific region. The image below show all the layers and masks I used, and the areas I targeted with each adjustment.
It is true that I can accomplish the same adjustment without Photoshop Layers & Masks, but adjustment layers combined with masks allow me a lot more freedom. I can fine-tune the adjustments I made on each layer without destroying the other layers. I can make adjustments to a single layer without having to retrace my steps. I can turn layers on and off to see what effect they have on one another. And I can add to or subtract from each mask to refine it at any time during the workflow.
I often save the image as a PSD file – with all those layers and masks intact – and return to it a few days later. In this way, I can keep track of all the adjustments I’ve made.
So, layers and masks let me take my blended image to the next level, and they allow me to preserve the processing steps I used to create the image. As my workflow gets more complex, layers and masks allow me to keep track of each adjustment, and gives me much greater control.
PS: You can do this with Lightroom’s adjustment brushes as well, but the the mask created in LR have limited controls as compared to those created in Photoshop.