Office hacks: Frequency separation grinding out the most real beauty

Nowadays, it is very popular to beautify photos through software, and even most camera applications have built-in beautification functions themselves, so that the beautification process is completed while taking photos, without the user having to worry about it at all. However, while we enjoy the convenience of automated processing, we can’t avoid the problem of excessive and uniform beautification, and automatically beautified photos always give people a false impression. If you want to get a beautiful but realistic photo, the use of frequency separation technology is a good solution.

High and low frequencies in images

Frequency in an image mainly refers to the density of details, such as wrinkles and pores on the skin, human or animal hair, textures on textiles, etc., small and dense, these are the high-frequency part. On the contrary, like the sky, clouds, shadows and other color block area is a large area of the low-frequency part (Figure 1). The so-called frequency separation (Frequency Separation), is the image of the high frequency and low frequency decomposition into different layers, and then edited separately, so as to beautify the image at the same time can retain the original real details.


Figure 1 High and low frequencies in the same image

Quick image frequency separation

Start Photoshop (CS5 version for this article) and open the image to be processed, then press F7 to bring up the Layers panel, drag the “Background” layer to the “Create New Layer” button at the bottom of the panel, and release the mouse button to duplicate the layer. Follow the same method to duplicate a total of two layers, double-click the layer names to rename them “High Frequency” and “Low Frequency” respectively.

We will extract the low frequency data first, so hide the “high frequency” layer for now and click to turn off the eye icon in front of it (Figure 2).


Figure 2 Duplicating multiple layers

The blurring process hides the details in the image, leaving mainly the low-frequency data. In the Layers panel, click the “low-frequency” layer, and then click the “Filter → Blur → Gaussian Blur” menu command, in the resulting dialog box will be set to a radius of 5 to 8 pixels, click “OK ” (Figure 3).


Figure 3 blur effect to hide the details in the image

Next, extract the high-frequency details from the image. Select the “high-frequency” layer, mouse click to light it in front of the eye icon to display, and then click the “Image → Apply Image” menu command, in the pop-up dialog box set the application of the layer just created the “low-frequency “Layer” layer, blend model for “Subtract”, compensation value set to 128, scale value set to 2 (Figure 4). After clicking “OK”, only the extremely detailed part of the image is left, and all other areas become gray (Figure 5).


Figure 4 Application Image dialog


Figure 5 High Frequency Image

Now we set the mode of the “High Frequency” layer to “Linear Light”, we will find that the effect of mixing the two layers is exactly the same as the original image, the only change is that the high frequency and low frequency have been broken down into two different layers, which can be independent editing.

Retaining details to refine the image

Next we can use all the tools in Photoshop to fine tune the image, adjust the brightness, remove defects, etc. Generally speaking, we can mainly edit in the low frequency layers, as long as the high frequency layers remain untouched, we can retain as much detail of the original image as possible, without the damage of retouching.

In order to make the person’s skin more smooth and delicate, you need to blur operation. Here we enter the “low-frequency” layer, properly adjust the brightness, and then execute the “Filter → Blur → Gaussian Blur” command, you can properly increase the intensity of the blur, even if the character blurred does not matter (Figure 6), later in the re-use of After the “high-frequency” layer is displayed, the original details on the skin will be restored, and the overall image is brighter and more colorful than the original (Figure 7).


Fig. 6 Super blurred image in the low frequency layer


Fig. 7 After blurring and highlighting the low frequency, the high frequency layer is re-layered, and the whole image becomes bright and delicate, and the original details of the skin are quickly recovered.

Easy makeup application

Frequency separation gives us more room to play, and on top of that, we can easily make up parts of the character, and even try various makeup effects in different areas of the character’s face. In this example, we feel that the character’s eyes are rather dark, at this time, you can select the lightening tool in the toolbox in the dark part of the painting, you can find that the eyelids become brighter, while the original part of the eyebrows are not affected.

Further, we can select the brush tool and then set a more vibrant color (such as red) to apply a bright lip gloss to the character. Since we are only working on the “low frequency” layer, the high frequency details such as the texture and highlights of the lips are not affected, making the final result very realistic (Figure 8).


Figure 8 High-frequency details make the added lip gloss effect close to the real one

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