Photoshop adjusts photo bias using 18-degree neutral gray points

I will be from the following three aspects of the elaboration: one is the need to grasp the knowledge of the point; the second is to adjust the idea of color; the third is the Photoshop procedure.

One, need to master a few knowledge points. Learn software, do post-processing, to achieve an artistic realm, you must master the software associated with or related knowledge. Here are a few concepts to look for 18 degrees gray

It is helpful to adjust the image's partial color understanding.

1 "Pixel: is a digital image of a minimum unit, shape: There are rectangular, square, PS in the pixel is square. A pixel has only one color, like a large and small, unable to determine its specific size.

The more pixels a photo has, the richer the color and the higher the sharpness.

2 "white field, black field: PS There are three kinds of straw white, gray, black. Used to draw the color of digital images. Here the white field, black field is not refers to the digital image itself white and black pixels, but the picture reflects the reality

Scene of the white and black place.

3 "threshold: That's the point!" For example, the tipping point is white, but the tipping point is black. This tipping point can be defined by itself. The threshold value in PS is actually based on the brightness of a picture

Black and white demarcation value, the default value is 50% neutral gray, both (RGB is 128, brightness higher than 128 (<50% gray) will be white, lower than 128 (>50% gray) will become black.

4 "Color order: is the color spectrum of the ladder changes." RGB in PS from Black to white, that is, from 0 to 255 have 256 levels of color values.

5 "Difference: Also in this understanding, to supplement some data between discrete data." In the Photoshop image, the pixel increases between pixels and pixels. )

6 "18 Degrees of gray: the camera gives you the recommended exposure combination, after the film, you light the point of the gray value (red-green-blue three-color value of the arithmetic average) must be 128 (256 is pure white, 0 is black).

Such a grayscale, is the reflectivity of 18% of Gray, also known as the ash. 18% how to calculate out, I do not know, the estimated scientists can not explain, so understand.

These, in their own understanding on the basis of the narrative, it is inevitable that there are not rigorous, wrong place, please understand.

Second, adjust the idea of color.

We all have feelings, any camera taken out of the photos are different color, any one display color is not the same, or even a brand model of the display color is also different.

To this end, adjust the color can not use the naked eye to judge whether accurate, the only way is to use the number to determine, this is the hard truth.

PS, with 18 degrees of gray to adjust the color of the digital image is very accurate, but also very professional. How to determine 18 degrees of gray? We'll use a few of the previous points to find the 18-degree gray pixel, through 18 degrees of gray

Pixel to balance the entire image color, so that the entire digital Image color is corrected.

Because 18 degrees of gray is a digital image of RGB values are 128 when the gray reflection rate. So, first of all to determine the digital image of the RGB value is equal to 128, in a color image if the image is found

The Black field and white field in the actual scene, the threshold value of RGB 128 can be obtained by the difference calculation, then the range of the threshold is narrowed, and the pixel of 18 degree gray is computed,

It simply corrects the color of the whole color picture.

Third, photoshop operation steps. Here, use a photo of the general practitioner's teacher, Apricot portrait, to specify the procedure. Thank you to the general practitioner for the work of the teacher.

We observed that there was a bias in this piece.

Turn on the curve adjustment, use the black eyedropper to draw the darkest pixel in the image, and click OK.

Then adjust the curve, using a white straw to draw the image of the most white pixels, and then click OK.

This is the black and white field selection steps to see the image has changed greatly.

Below start looking for 18 degrees gray pixel, very key yo! First copy the background layer and get a copy of the background layer.

Then, from the Edit menu, click Fill, and in the Fill dialog box, select 50% Gray to fill.

This is the effect after the fill. Category:

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