My intellectual curiosity drew me to Photoshop LAB Color written by Dan Margulis. The author warns that the topic is difficult. I was able to understand the first chapter in concept and technique. It was very useful and i have used it to improve a couple of images that have vexed me. The exercise in chapter 2 has me stumped. I am lost as i went deeper in the book and i was curious if there are others that have found the techniques useful. Are there other resources that can help with me to understand some of the additional concepts so that i can apply them on other types of images?
Lab can be very useful on occasion and perhaps accomplish some things which would be more difficult or time consuming in any RGB space (at least for me).
On the other hand I have a feeling that sometimes its benefits have been oversold, nevertheless the areas I find most useful (agreeing with others that have posted before me)
1. Making colours pop without introducing artefacts that may be apparent using other methods. So called Picture Postcard workflow. Useful for accentuating very subtle changes.
2. Potential to repair and replace a damage channel (often blue) in an RGB file and reduce noise in the process.
3. A nearly penalty free method to reduce/eliminate colour noise
4. Making gross changes to colour e.g. Red car to green blue or any other shade. Usually accomplished with little in the way of masking with just the use of Blend IF
5. Finding a starting point mask that may be better than RGB or CMY
Generally I would forget about it (most of the time) for 8 bit images as the risk of introducing nasties is increased you losing around 30 levels from the 256 you have available. Working in original 16 bit data the losses are likely to be any real concern. I am sure there are exceptions in both cases
Quick example where it may be more useful than other modes. Client gives you a T shirt to shoot or T shirt image. Bad news he only has a green one available but has a range of colours he needs to show in an ad. and of course it is needed yesterday. He is able to give you however a precise colour perhaps Pantone or colour swatch etc.
Some like to use a Gradient map in PS. I invariably find that I can get a better looking result in Lab in a much shorter time than using Gradients. Below is a quick play changing the colours of a green T shirt image. No masking needed in this case for skin tones and jeans just used Blend If sliders
Click on the Thumbnail. Image should change after a second or two