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Posts tagged “LAB Mode

JUST WHAT DOES A LAB INVERSION DO?

Image of a purple wildflower on a black backgroundThis week I have been reading a book, The Way of the Digital Photographer, from one of my favorite photographers and Photoshop people, Harold Davis.  As always, I love reading his books because they are not over-complicated, but have a fresh approach to post-processing your images. The above is the first time I have used his LAB inversion technique and I really liked the results. Harold has a nice website article called Using LAB Color Adjustments that goes into a lot more details on how to get this effect and even more creative results than what is shown in this blog. He has a great tutorial in one of his older books called The Photoshop Darkroom if you really want to understand it. The bottom line is that by switching LAB mode and inverting the LAB Channel at the top of the Channels panel, all color values in the image will be swapped with their opposites, and Harold says it can create electric blues. With just the L (Lightness) channel selected, the grayscale information is reversed so that the black becomes white and white becomes black – this is great when the image is on a white background and you want it on black as shown above. With the “a” channel inverted, the magenta pixels become green pixels and the green become magenta. Same with the “b” channel when it is inverted – blue pixels become yellow and yellow pixels become blue. Once this is done, he likes to adjust the blend modes and layer opacities for more effects and to use layer masks to apply some of the results to localized areas of the image. Pretty creative process here!

The above image is of a little tiny wild flower plant growing on my porch – just hanging in there. I had to lie down flat to get the picture since the plant is no more than 2 inches tall with a white cardboard background set behind it. The original image from Lightroom is shown at the bottom of the blog so you can get a feel for how this technique can really change up an image.

After the doing the basic Lightroom adjustments which included sharpening the main flowers, the image was brought into Photoshop where the image was changed to LAB mode first. To do this, go to Image -> Mode -> LAB. This needs to be done on a flattened layer since the LAB mode does not read all Photoshop layers info like masks and adjustment layers correctly. Therefore you may want to duplicate your image at this point and use it in LAB mode. Once in LAB mode, duplicate your layer (CTRL+J). Go to the Channels panel where you can now invert the whole LAB image, or the individual channels, especially the L channel where only the luminance info resides. Just do a CTRL+I if using all the layers, or highlight the individual channel and with all the eyeballs on, CTRL+I to invert just the one channel. For the above just the L layer was inverted, but I tried them all. Very interesting results with each. Instantly this beautiful black background showed up with the soft colors in the background objects. At this point you can try localizing the effect with a layer mask, or changing the blend mode of the inverted layer. The image now needs to be flattened again so that the colors do not change when converted back to RGB. Go back to Image -> Mode -> RGB to continue the processing. The steps are listed more clearly further down in the blog. In this image a little more sharpening was done and Melissa Gallo’s Painted Textures Taupe Canvas was applied.

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Image of a display of Margaritaville mixers that have been inverted in LAB modeAbove is another example of what a LAB inversion effect does to the L channel. This image was a lot of fun to do, but it did take a lot clean up – I basically wanted the colors to stand on there own – an image of mixers at Margaritaville in Orlando just happened to have the elements I wanted to show. The original image I posted on my Mixers for Margaritas! Tidbits Blog. (Here are the details on what was done to get the above image using the image from the blog: This blogimage was flattened. The layer was taken into LAB mode where the layer was duplicated, then in Channels panel, the L channel was inverted. Back in Layers panel the blend mode was changed to Linear Burn, then flattened before returning to RGB color mode. The layer was duplicated and taken into Topaz Simplify 4 where only black lines were applied – only Edges section is used. Once out of Simplify, went to Select -> Color Range where the Highlights were selected with Fuzz 1, Range 255, and Inverted checked. A layer mask was added and the selection applies. To get a little more black line emphasis, PS Ink Outline filter was applied using Harold Davis settings of 11/5/19. The Color Range line layer was set to 59% and the original Simplify layer was deleted. Some clean up was done to finish up.)>

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Image of the Incredible Hulk Coaster done with a LAB inversion effect
This image of the Incredible Hulk Coaster (to see a video from the front seat of the ride, click here) at Universal Studios in Orlando, Florida, is a good example of what an image will look like with the “a” channel inverted in LAB Mode along with the L Channel. In this case the L channel caused the background to turn to a nice dark color since it was originally light, and the “a” Channel conversion caused the roller coaster to become a red-orange color from the original green-yellow. To help you follow along, here are the LAB steps that are basically the same for  each image:

1. Opened image in LAB by going to Image -> Mode -> LAB.
2. Duplicated layer and highlight it.
3. Go to Channels Panel and select “a” channel – invert (CTRL+I) the channel.
4. Highlight the L Channel and invert it also.
5. Click LAB Channel eyeball so all channels are turned on.
5. In Layers Panel, changed blend mode to Linear Light. (Could add a black layer mask at point and add only parts of the effect into the image.)
6. Go to Image -> Mode -> RGB and choose Flatten Image.

Pretty dramatic change but I like the results. To make the reds and blues really vibrant, just before converting back to RGB Mode, the LAB layer with the inverted channel changes was changed to a Linear Light blend mode. Then, once back in Photoshop, the layer was duplicated and set to Multiply blend mode at 52% layer opacity just to make it more vivid. The Lightroom original for this image is shown below.
Image of original photos of purple wild flowers and roller coasterAs you can see, this LAB conversion technique does have some possibilities. It tends to give a graphic feel to your image. It can pick up a little noise and I had to run Topaz DeNoise 5 at an overall setting of .39 to the coaster image – then added a black mask and painted in areas that looked too noisy – surprisingly it was not the dark background (since it came from a light sky) but the reds and blues. This LAB Inversion effect is definitely something to remember when you want to do something very different to an image – pretty easy technique to follow and some really interesting results can be obtained. Hope you will give it a try!…..Digital Lady Syd

Digital Lady Syd Related Blogs:
Unsharp Mask Filter In LAB Mode


Unsharp Mask Filter In LAB Mode


I have been experimenting with all types of sharpening methods over the last few months. I really liked the High Pass Sharpening method that is very popular, the new improved Sharpen Tool in Photoshop CS5, and the Smart Sharpen Filter that so many use. Recently I read Harold Davis‘ book The Photoshop Darkroom where he gives steps to sharping in the LAB Mode. I have now started using this method – it takes a little more time to do, but I believe it really gives the best results. Since I take a lot of time with my images, like to print them, and don’t batch process, it is important that each image gets the best sharpening I can do.

The above image of the fruit shop along the road on the Big Island in Hawaii is an good example of how nice the sharpening can be in an image. Both Nik Color Efex Pro 4 and Topaz Simplify 3 (see sidebar at my Tidbits Blog for website link) were used in Photoshop to get the rich colors. The LAB sharpening was done after most of the adjustments were made to the image in Lightroom and Photoshop.

Why use LAB Mode sharpening? The most important reason people use it is to keep the colors true and not be influenced by any color shifting that other RGB Mode sharpening may produce. By using a black layer mask, the image is first over-sharpen and then just areas that need the sharpening can be painted back into the image selectively and to various degrees so it does not  have that over-sharpened look. This process also works really well on portraits where just the eyes are sharpened or on areas you want to draw attention to a certain part of an image.

The workflow steps to get this effect are easy:

1.  Apply most of the filters and do  clean up to your image before the next step. Just be sure there are no adjustment layers in the document or they will be discarded upon the conversion. You will need to save the image as an unsharpened version and then flatten it to proceed.

2.  Go to Image -> Mode -> LAB – Click “Don’t Rasterize” and “Don’t Merge” buttons.

3.  Duplicate the layer by clicking CTRL+J.

4.  Go to the Channels panel and highlight the L channel.

5.  Turn on the top eyeball so all channels are showing but only the L channel is highlighted.

6.  Go to Layers Panel and to Filters -> Sharpen -> Unsharp Mask.  I like Harold Davis’s recommendation to start with these settings and adjust from this point.

Radius  2.7   – The higher the Radius setting, the more sharpening occurs
Threshold 9   – The lower the Threshold setting, the sharper the image
Amount  – somewhere between 50-120

Watch out for noise enhancement, especially when adjusting the Amount slider.

7.  Add a black layer mask to layer by holding down the ALT key and clicking the Layer Mask icon at bottom of Layers Panel. Using a soft white brush set to 30% opacity, paint back in the areas you want sharpened leaving areas with noise or over-sharpened edges unpainted. Paint over several times to enhance the effect.

8.  Go to Image -> Mode -> RGB and press the “Don’t Flatten” button. Now you can add your Curves Adjustment Layer and frames to finish up.

Dan Margulis (one of the first three people ever inducted into the Photoshop Hall of Fame) is the most knowledgeable person when it comes to using the LAB Mode and has written the best book ever on the subject, Photoshop LAB Color. He covers LAB sharpening very thoroughly.


Here is another example of how great this type of sharpening works – it is great to be able to localize where the actual detail is emphasized. This old vintage car was parked in front of the Casa Monica Hotel in St. Augustine, Florida. It is a three image HDR photo processed using Katrin Eismann’s workflow – see my blog HDR Using Photoshop Merge to HDR and Nik”s HDR Efex Pro and Silver Efex Pro? Wow! (used Granny’s Attic preset in HDR Efex Pro and Structure Harsh in Silver Efex Pro). Nik’s Viveza 2 was used to increase the detail and color in the wheels and curtains in the windows. Then it was taken into the LAB mode and processed using the Unsharp Mask Filter (settings Amount 98/Radius 9.4/Threshold 1). Using a brush set to white at 30% opacity, the wheels, curtains and lettering were painted back in. I wanted the rest of the image to have that grungy old feel to it which HDR Efex Pro gave the image. OnOne PhotoFrame (see sidebar at my Tidbits Blog for website link) Kevin Kubota Flower was added as a last step.


The LAB Unsharp Mask was used on this image of an elephant puppet from Burma that was on display at the Hilton Waikoloa Village on the Big Island in Hawaii. To see how it was processed see my blog Nik Color Efex Pro 4 Just Does It Right! The sharpening was applied as the last step and it was selectively painted in to just the details in the elephant but not the background. This really made the details in the puppet stand out.  Also all the images but the Lightroom image in my blogs Can a Pseudo HDR Image be as Good as the Real Thing? (Part One) and Can a Pseudo HDR Image be as Good as the Real Thing? (Part Two) used this method on the bicycles very successfully.

I am not really sure why, but I definitely see an improvement in sharpness using the LAB method of sharpening. There are times when not that much needs to be sharpened in an image and the Sharpen Tool is enough or Nik’s Viveza 2 adds enough sharpening so this process is not necessary. I do think it works really great on my landscape and HDR images where I want a very clear edge on most of the objects. Give this easy method a try and see what you think…..Digital Lady Syd