Lab color space

Yes it's a wonderful colour space and perfectly suited to colour adjustments etc. Thanks for the suggestion Chawil, I did touch briefly on Lab in my Sharpening series - Reducing Colour Noise During the Sharpening Process, although you're right, Lab's a big subject and could easily fill a series by itself, or at the very least a couple of right-to-the-point videos!

Thanks for suggestion

Matt

I have been right through this a couple of times. The first part is just a show-off piece designed to demonstrate how easy it is to change colour using Lab ("Buy my book!") but the last part is much more interesting. In particular the technique of replacing one colour channel with another in RGB to improve the image of the leopard overall and then using Lab for the colour looked very effective. If you do a series on Lab perhaps you could explain this technique more fully.

Thanks for all your hard work. I have found this to be THE most helpful site for improving my images and look forward to seeing more videos in the future.

By the way have you ever thought of accepting donations? I would be happy to contribute, although as a retired pensioner it wouldn't be much, but you have given me so much knowledge that I would like to give something back.

Regards

PS You're right, it was the "Sharpening" series; it's just that there was so much in "Levels" that I got them confused.

Hey chawil,

Thanks for your kind words, I really appreciate you saying and I'm glad you're finding the videos helpful.

Lab is an interesting subject and there's still quite a lot of theory involved. I'm sure I still have things to learn about it but doing a series would be fun. It's a great knowledge to have for colour adjustments and the like. Feel free to post a link to the Lab tutorial you're citing, I'd be interested in viewing it.

As for donations, thank you very much for the offer, and I'm pleased you regard the site and my videos so highly. At present I don't have any facilities for donations but it's something I hope to add to the site in the future. I'm also looking at making my video series available to download in maximum 1024x768 quality for a minimal fee. It's just a way to generate a little money to maintain server costs etc. All the videos would remain free to view however.

Thanks once again

Matt

This tutorial is on YouTube. Its title is "Photoshop World: Lab Color with Dan Margulis - PixelPerfect", my address bar gives the link as:

http://www.youtube.com/watch?v=KhfRynutmQM

but if you do a search on 'photoshop lab tutorial' you'll definitely find it in the results.

The technique I was curious about for replacing a colour channel uses the following steps:

1. in RGB duplicate the background layer (make sure you're working on the duplicate layer)
2. open Channels
3. select the best looking colour channel, i.e. the one that has the most detail
4. open 'Image/Apply image' and use it to replace the the worst looking channel
5. go back to Layers and change the Blend Mode to 'Luminosity'

This should give you a much better image overall, however it will probably wash out the colours, which is where Lab comes in.

Note - if all the channels are about the same quality you can skip directly to the Lab adjustment.

Hope this is useful,

Charles

Yeah that's an interesting technique for sure. I like the way the Luminance blending mode in RGB is like a gateway to the L channel in Lab. I've never been one for messing with the live channel data like that but I guess you could easily save the original channel as an alpha channel if you were that way inclined. Have you played with example much yet? I'd be interested to hear about the results on a broader range of photographs.

Good video though!

Have tried it on a couple of my photos where there was one channel that really seemed washed out and it worked a treat. There are several more videos from the PhotoShop World show and they're all good. However these guys are pros who've been working with PShop for years and tend to go at about Warp 9 so I have to watch them two or three times to get the idea; but they're well worth watching.

And there's really no need to save the channel since you're working on a duplicated layer. If you don't like the results just delete the layer and start again! The whole technique takes less than a minute, the trick is knowing about Image/Apply image which I had totally ignored before watching this video.

Yeah it looks like a top tip although in my experience the channels are reletive to the whole image, not layers, so I don't think duplicating a layer would leave you able to bring back the original channel.

I guess it just shows the number of techniques available once you're willing to switch out to Lab. I remember a few years ago Apply Image and Calculations were the backbone of successful manipulations in Photoshop, sometimes we forget just how much they still have left to offer!

See this article and video for a more info:

http://www.adobepress.com/articles/article.asp?p=727922&seqNum=4

As you can see Apply Image is relative to layers. In older versions (e.g. 2.1) before Layers were incorporated into PhotoShop, it did work across the entire image and was the only way to achieve some of the effects we now get with layers. Now it works only on the active layer.