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Using LAB Color Mode to Improve the Color Quality of Photos

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Quite a number of people are not really familiar with the LAB color mode and how this can be used in order to color correct and enhance photos. In this article, we will go through the various steps involved in this advanced Photoshop technique to improve our photos and also achieve the same result in RGB, which may take us longer to complete the process and may not provide us with the same great results that can be obtained in LAB.

A Brief and Simple Introduction to LAB Color Mode

This section tackles some of the basic stuff about LAB color mode and you have the option to skip it and proceed to the practical technique and steps involved in using LAB. However, this section is a must read if you need to strengthen your basic understanding of the theory before you start learning about the more advanced aspects of the applications.

So, what are the basic differences between RGB and LAB? Most of us are already aware that we have 3 color channels in the RGB color mode – Red, Green and Blue. These channels are combined to form the colors that comprise the RGB color wheel. Green and red are combined to produce the color yellow, blue and green are combined to produce the color cyan and red and blue to produce the color magenta.

Improve Photos with LAB Color Mode (1) – LAB color mode consists of 3 color channels: luminosity channel, green-magenta channel and blue-yellow channel. The Luminosity or “L” channel contains all the essential information on luminosity and it is generally referred to as the B & W version of the photo. On the other hand, the “A” channel contains all the greens and magentas of the photo while the “B” channel contains all the blues and yellows.

You may be wondering what happened to the channel for red cyan. There is no channel in LAB for red cyan as these colors are produced when the channels “A” and “B” are combined. Red is obtained when the same amounts of yellow and magenta in channels “A” and “B” are combined while the color cyan is obtained when magenta and green of equal amounts in channels “A” and “B” are combined.

Improve Photos with LAB Color Mode (2) – It would be easy for us to observe that the colors are somewhat not right. The blue color is a bit too close to cyan; the green color has this “cyanish” look while the yellow color has a distinctive brownish element.

The reason for this is that the LAB color mode is specially designed for the reproduction of colors in the manner that these are seen by humans while the RGB color mode is designed in the manner machines see these colors. It is related to the simultaneous contrast and the manner by which specific colors are perceived and judged based on the actual colors around them. While this is not a precise description of the LAB color mode, this should be enough to get us started. To learn more about the technical aspect of the LAB color mode, you need to check out the article on the subject at Wikipedia.

5 Simple Steps in Photo Enhancement

Begin by selecting a photo that requires some degree of enhancing and open it using Photoshop. A photo that is ideal for this activity should be fairly dark with light bluish color cast and somewhat bland colors. It is highly recommended that you initially do what is referred to as a “channel walk” and evaluate how the color channels look. Come up with a few color samples in the lightest and darkest spots of the image and try to determine whether there is a color cast or not. These steps may require some time and for our purposes, let us assume that we have about 3 minutes to correct the color and improve our image.

Now, let us go on and LAB our picture.

Step #1 – Go to Image/Mode/Lab Color

There shouldn’t be any change in the picture

Step #2 – Go to Layers/New Adjustment Layer/Curves

There may be some variances in the histogram of channel for lightness, but you can follow these guidelines.

Make an “S-Curve.” Create a point by clicking an area on the upper section of the histogram and dragging it upwards. Then create another point on the lower section of the histogram and drag it in a downward direction. Make sure that you don’t go overboard when making the adjustments in the highlights (upper section) and the shadows (lower section) of the histogram. You must aim for a perfect balance in the distribution of a balanced tone, where there are equal amounts of shadow and light.

The creation of an “S-Curve” results in more contrast to the middle tones, while the shadows and highlights are flattened. Carefully examine the histogram and when there is an empty space at the right side, drag the slider for the highlights up to the point where it is positioned right under the histogram values. This action will in effect establish the white point and add to the contrast of the middle tones. You can also adopt the same procedure for the shadow slider, but you have to make sure that you do it on a lesser extent as this would produce ugly black artifacts.

Shift to “a” channel and then drag the right and left slider towards the center making sure that the adjustments are of equal amounts. It would be of great help if you are able to obtain a grid that is more detailed. Drag the sliders until you reach the first vertical line and then shift to “b” channel and go through the same process.

Step #3 – Transform the “background” layer to smart object

You can achieve this objective by right clicking the layer and choosing the control “convert to smart object.”

Step #4 – Go to Filter/Blur/Surface Blur

Designate high values. You have to remember that a high radius and threshold value would result in more blur. There is no reason to worry if you get an image that looks blurry as this can be easily fixed. Find the little icon towards the right of the smart filter for the surface blur and right click it in order to activate the blending options. Then choose the color for the blending mode. This procedure will effectively reduce or remove any color fringing or color noise from the image.

Step #5 – Go to Filter/Other/High Pass

Apply a small radius up to the point where the details are about to emerge from the gray section. Then double click the icon for the blending options and convert the blend mode into soft light.

An alternative procedure involves the use of an Unsharp Mask or a Smart Sharpen and then change the blend mode to luminosity. This procedure applies the sharpening exclusively on the luminosity channel, leaving the color channels free of noise. You may opt not to use these filters on the image as there is the tendency that it would add noise to an image that is already noisy. This is the ideal option if, in your assessment, the degree of clarity obtained through the High Pass Filter is enough already. On the other hand, if you have an image that is blurry, then you may apply some degree of sharpening using the filters cited above, and don’t forget to shift your blending mode to luminosity when you perform this procedure.

The steps discussed in this article are much easier and faster as soon as you get the hang of the entire process. A person who is already familiar with these steps can complete the entire process of transforming a relatively bland picture into an image that is pretty decent looking in about 3 minutes.

You can start using the LAB color mode and gradually integrate it into your regular workflow. You have to remember that the procedure that was discussed in this article is not absolute when it comes to photo enhancement. Try to adapt it so that it would suit your needs and make those images look great in just a few minutes. M.A.H.


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