Principle and discussion of self-setting filter
Let's take a look at the following groups of effects
Impatient people will say: "What Ah, the first is not sharpening it?" The second one is ... Is sharpening, yes, but not sharpening filters, but "custom" filters, I believe many people do not know what it is for, and it is difficult to find relevant information, the following is the official Adobe Commentary: Custom (Photoshop) allows you to design your own filter effect. Using the custom filter, you can change the brightness values for each pixel in the image, based on predefined mathematical operations called convolution. To reassign a value to each pixel based on the surrounding pixel values, similar to the addition and subtraction of channels, you can store custom filters that you create and use them for other Photoshop images.
To create a custom filter:
1 Select "Filter" > "Other" > "Custom".
2 Select the text box in the middle, which represents the pixel to be computed. Enter the value to be multiplied by the brightness value of the pixel, from 999 to +999.
3 Select a text box that represents adjacent pixels. Enter the value to be multiplied by the pixel of the location.
For example, to multiply the pixel brightness value immediately to the right of the current pixel by 2, enter 2 in the text box immediately to the right of the middle text box.
4 Repeat steps 2 and 3 for all pixels to be computed. You do not have to enter values in all text boxes.
5 for zoom, enter a value to use to remove the total brightness of the pixels contained in the calculation.
6 for "offset", enter the value to add to the scaling calculation.
7 Click the "OK" button. The custom filter is applied individually to each pixel in the image.
Use the Save and load buttons to store and reuse a custom filter.
To understand this filter, I created a pixel graph, like the next, to look at the brightness of the pixels inside the red circle.
Use Photoshop custom filter to modify photo Sharpening process TutorialClassification: