# Frequency decomposition in "Photoshop". Photoshop tutorials for beginners

## Introduction

Frequency decomposition in "Photoshop" raises many questions. And if two years ago there was little information on this subject, now, of course, there are answers on the Web, but all of them are given in fragments and are not always clear. It is because of this that it is difficult for beginners to understand the frequency decomposition in Photoshop.

Tutorials from professionals on the Internet are given for a reason. Many companies put forward a requirement for a retoucher job to know how to make frequency decomposition in Photoshop at least at a minimum level. But even tech freelancerscome in handy - it will increase both the speed and the quality of work.

## What is this?

Frequency decomposition is a decomposition in terms of frequencies. The term is used not only in the field of portrait processing, but also in mathematics, music, etc. For a retoucher, this means that a photo is decomposed into several layers (frequencies), for example, a detail layer and a tone layer, each of which is edited separately from the others.

Because this article is included in the "Photoshop" tutorials for beginners, it will focus on both explaining the principles of frequency decomposition itself and the little things that professionals have long been familiar with.

## History

Computer graphics and processing are based on mathematical laws, although the creators sometimes don't care about them. Thus, the frequency decomposition also went from the Fourier decomposition into frequencies: first, the mathematical method was borrowed by radio engineers, then by musicians, and, finally, by retouchers.

Photoshop lessons for beginners rarely contain this information, and there really is no need in mathematical formulas. However, what the frequencies are will still be discussed a little further.

## Why is this needed?

Frequency retouching is used when it is necessary to process ala natural. In other words, if the end result should be a natural, not glossy finish. Also, processing in the manner described below is much more accurate and of high quality and means the highest degree of skill.

## Different from usualprocessing methods

Glossy photo retouching in "Photoshop" is carried out using masks and various types of blur. This makes the skin in the portrait too soapy and "seems to be processed". For certain formats, this result is desirable, but in the case of natural portraits, the processing should not be visible. This is done by separating the layers from each other - retouching one of them, we do not affect the rest.

## Can it only be used for portraits?

Of course, there is no "use only for portraits" taboo for this technique. And although from this, and a number of other articles on the Internet, you might think that it is most effective for them, it is not. Portraits make up the lion's share of the photography market and their retouching is always in the first place, but frequency decomposition is universal and great for any shots where there is a need to edit details separately from each other.

## How many frequencies to spread?

There are two types of frequency decomposition in Photoshop:

1. The skin is decomposed into two frequencies - tone and details. On the first layer, the skin is smoothed, on the second, defects (wrinkles, pimples, etc.) are removed.
2. Decomposition is made in three frequencies - high, medium and low. See below for more details.

## First steps

Regardless of which method you decide to use, you first need to open the photo in Photoshop and makeseveral copies of its layers - the number depends on the method. In the first case, two copies of the layer are created, in the second - two.

## Frequency decomposition in "Photoshop" into two layers

As mentioned above, skin tone is taken as the first layer for this method, details are taken as the second.

After making two copies of the layers, it is recommended to create a separate layer group for them. This is optional, but it is considered good form for retouchers and generally simplifies the work. Groups in Photoshop are a feature of professionals.

Also, for the convenience of work, it is recommended to give the appropriate names to the layers: "Tone" and "Details", and "Details" are above the "Tone".

Next, photo retouching in "Photoshop" begins in the usual mode: open the "Tone" layer and apply "Gaussian Blur" to it.

Blur values usually range from 7 to 10 (the number of themes is higher the larger the image. In some cases it can go up to 15). The exact number is selected by the retoucher independently - depending on the size of the photo and by eye. Perfect blur - when the skin is smoothed out, but the shape and main details are still readable.

After that, you should go to the second layer. It must be prepared in advance. To make all the details "cut through", the "Color Contrast" filter is used. In Photoshop, English sounds like High Pass. Located in the menu Filter (Flter) - Other(other). In general, this article describes the frequency decomposition in Photoshop step by step in Russian, but those who use the program in English will also find it useful.

The sharpness of "Color Contrast" can be adjusted in the same way as "Gaussian Blur". The value is similar - if the number 12 is selected for the "Tone" layer, it will be equal to 12 for the "Details". The result of applying the filter is a gray embossed image.

## Second stage

For the "Details" layer, the "Blend Mode" is changed to "Linear Light". If the image is too contrasty, go to the Curves tab and reduce the contrast. Alternative: reduce contrast the old fashioned way by lowering the Contrast setting.

The frequency decomposition itself is already done - it remains only to remove the defects with a dotted brush. This is a simple but painstaking job. It is recommended to take a small brush with a slightly flattened shape (set in the parameters). She needs to go over the entire image and remove the defects.

Attention! When removing small pimples and mimic wrinkles, you should leave those lines that make the photo anatomically correct and affect the similarity of the faces in the portrait.

## Remarks

The simplest technique is described, but there is another variant of this technique. Using the method described below, you can perform frequency decomposition in "Photoshop CS6" and higher.

When working with the "Details" layer instead of a filter"Color contrast" switch to "External channel" (image tab), in the parameters from the drop-down list select the "Tone" layer (this is not a typo, really select "Tone") and click OK.

The Blending Mode is then also changed to "Linear Light". All the following actions are performed in the order described above.

Important! If the "Gaussian Blur" turned out to be uneven, and a larger value of the parameter "blurs" the details too much, you can blur the uneven areas a second time using the "Lasso" tool. It is able to select the necessary parts of the image, after which the blur is applied only to the selected areas.

## Decomposition into three frequencies

Frequency decomposition into three layers in "Photoshop" is performed according to the same rules as for two. On the other hand, the three-layer decomposition is closer to its ancestor - the Fourier decomposition, and with the help of it it is easier to explain the principle of the decomposition itself.

So, the upper, middle and lower frequencies are taken as a basis. In the area of retouching in the upper frequencies there is information about the general form, in the middle - the texture of the surface, as well as all defects and spots, in the lower - information about the light and transitions. After this description, it is not difficult to conclude that the "Tone" and "Detail" layers are nothing but high and low frequencies.

Mid frequencies in the above method merged with high frequencies and edited independently, because the method of frequency decomposition into three layersmuch better and better quality. Consider it.

## Frequency decomposition into three layers in stages

Before decomposition, the photo should be pre-processed. It is recommended to create one copy of the layer for this.

Interesting! A copy of a layer can be created by clicking the mouse from the desired item of the context menu or by clicking on the corresponding icon at the bottom of the layers window. Also, this action is performed using the key combination Ctrl + J. Keyboard shortcuts are of great importance in the work of Photoshop, they speed it up and make it more comfortable. Of course, at first the combinations will not be remembered and will not be used automatically, but to endure the transition period of memorization in order to become a master is worth it.

Defects are removed on a new layer with a spot brush. This is less painstaking work than in the previous paragraph, since there is no need to remove small things - in this case, the brush size is taken larger and only what really catches the eye and will interfere with subsequent work is processed.

Next, three copies of the processed layer are created. They are called "High", "Middle" and "Low" respectively. This is done, as mentioned earlier, for convenience. You can start retouching both from high frequencies and from low ones - there is no difference.

The "Low" layer is overlaid with "Blur onGaussian". Unlike the decomposition method into two layers, the blur parameter can go up to 30. The main thing is to choose a number at which the skin tone will be uniform.

For the "High" layer, the "Color Contrast" filter is selected. The "Color Contrast" value should be three times less than the "Gaussian Blur".

Lifehack: write layer parameter values in their names. If the numbers are 30-10, they are easy to remember, but when working with 12, 7, it is better to write them down.

The "Low" layer will contain both blur (blur) and contrast. The blur value is equal to the "Color Contrast" value in the "High" layer (in this example, 30), and the contrast value is equal to the blur value in "Low" (10).

A group is created for all three layers. The decomposition is ready, you can start editing.

## What are each of the frequencies for?

The "Medium" layer contains all defects. Removing it completely is undesirable. To remove the bumps, you need to create a mask (Alt + mask icon at the bottom of the layers window), and then use a black brush to draw over the portrait in places where there are bumps.

The same way you can process the "High" layer to increase the uniformity of the skin tone. On the same layer, they work with colors - they darken and tint the necessary areas, even out the colors.

## Applications

In addition to studio portraits in which you want to remove a couple of pimples, before retouching by frequency decomposition in Photoshop, there will beset quite different goals. So, it can be applied in such cases:

1. It is necessary to correct the clumsy work of the makeup artist - in other words, to redo the makeup. It is also possible to apply make-up from scratch. In the latter case, it is recommended to have a photo of the same model with any other make-up for the authenticity of the application.
2. Soft muting of the texture of the skin - easy and accurate retouching, without the intervention of a spot brush and "blurred" blur.
3. Shave a man - requires a combination of frequency decomposition methods, with painstaking work, a good result is obtained.

## Working speed

Despite the fact that the method seems simple, after the decomposition itself is done, the work on all three frequency layers continues to be painstaking. An experienced retoucher works on such "little things" as shadows and highlights, image volume. Frequency decomposition is not a way to transform a photo in one click, but, on the contrary, a technique for deepening it.

Nevertheless, the mathematical basis of the method suggests how it can be automated.

## Programmatic ways

For "Photoshop" (and for "Gimp", its "Linux" brother, by the way, too) there are special plug-ins, as well as actions. All of them do not fully automate photo retouching (in the end, this is still a creative process), but they programmatically perform actions to create the necessary layers and their settings. It's significantsimplifies frequency decomposition in Photoshop.

Action (action - action, operation) is a file with the ANT extension, which is a set of operations in Photoshop. It can even be called a mini-program. An existing action file is opened using the "Window"-"Operations" tab.

Action for frequency decomposition, if desired, you can create yourself - manually perform all the above steps and go to the same "Operations" tab, and then click on the icon for creating a new operation. For convenience, it is also recommended to create several actions to create separately the first, second and third layers.

Actions for download are available on the Internet, but it is still recommended to create them yourself - first try the frequency decomposition manually, then understand how to use it, and then automate this process for later use. In addition, downloading from the Internet always implies the possibility of downloading a virus. So better play it safe.

Like any program, actions are editable, but editing what was written by someone else is more difficult. To the fact that each author makes the operation, first of all, "for himself", and only then, in a fit of generosity, puts it on the Internet for everyone to see.

## Conclusions

In general, frequency decomposition is a very powerful tool. The first method, in which the process is carried out in two layers, is closer to conventional retouching and only slightly opens the veil of the use of decomposition. The second one, being a modified mathematical operation, gives a huge scope for creativity. The article described the minimum possibilities of use, since its purpose is to talk about the decomposition itself, what it is and how to do it. And by delving into the topic a little more, you can find much more "chips".

Finally, it is also worth saying that one possession of frequency decomposition will not make anyone a brilliant retoucher. Like any tool, it only has power in experienced hands. So, you need to see the end result even before the first step is taken, notice the little things and only then choose which tool is best to fix them with.