What is the concept of pixel? What is layer mask?

Is made up of

Picture (image)

and

The letters of the word "element" are units used to calculate digital images. Just like photos, digital images have continuous shadows. If you enlarge the image several times, you will find that these continuous shadows are actually composed of many small squares with similar colors, which are the smallest unit "pixels" that make up the image. This smallest graphic unit can usually display a coloring point on the screen. The higher the pixel, the richer the sample and the more realistic the color is.

Layer mask can be understood as covering the current layer with a layer of glass, including transparency and black opacity. The former shows all, while the latter hides some. Then use various drawing tools (on the glass) to draw a mask (only black, white and gray). Where the mask is painted black, it will become opaque and you can't see the image of the current layer. When painted white, the painted part becomes transparent and you can see the image on the current layer. When painted gray, the mask becomes translucent. The degree of transparency is determined by the gray level of painting, which is a very important function in Photoshop.

(1) It is a special constituency, but its purpose is not to operate the constituency, on the contrary, it is to protect the constituency from being operated. At the same time, you can edit and process places that are not within the scope of the mask.

Although the mask is a kind of constituency, it is very different from the conventional constituency. Conventional selection shows an operation trend, that is, the selected area will be processed; On the other hand, the mask protects the selected area from operation and applies the operation to the uncovered area.

It can be said at that time: First of all, layer mask in PS can only use black and white and its intermediate color (gray). Black in the mask covers the content of the current layer and shows the content of the layer below the current layer, while white in the mask shows the content of the current layer. The gray in the mask is translucent, and the content of the next layer is looming.