What's Photoshop-305911?

Source: China Photoshop League Forum Author: zhangwei5009

What's 305911? is a mathematical expression, namely 0.3r+0.59g+0.11b. In Photoshop, what exactly is a mathematical expression of what is being computed? Some say it is the lightness in lab, some say it is grayscale in grayscale, and some say it is the brightness in RGB mode (that is, the brightness in the histogram). It is not very meaningful for the operator to study it, and the operation of the image has more subjective component. But it is necessary for researchers to figure out what it is. The formula itself is a fixed definition, and nothing needs to be specifically explained. The following is just a way of verifying whether it should belong to Yumingdo, grayscale or brightness. Before verifying its attribution, first 0.3r+0.59g+0.11b the expression to an image and calculates it. Just do the prep work first. Copy the red, green, and blue channels onto the layers.

Convert the 0.3R to the color order value, 0.3x255=76.5, and take the whole 77. Again as the diagram operation.

Merge layers and close. Convert the 0.59G to the color order, 0.59x255=150.45, and take the whole 150. Again as the diagram operation.

Merge layers and close. Convert the 0.11B to the color order, 0.11x255=28.05, and take the whole 28. Again as the diagram operation.

Then change the layer blending mode of the red channel layer and green channel layer to "linear dodge". Linear dodge is added, adding three layers of the same pixel value together.

Merges three channel layers. I changed it to a name called: 0.3r0.59g0.11b. This 0.3r0.59g0.11b layer is what we call the mathematical expression above. To complete this preparation, verify below.

Verify:
Open the histogram and change channel to brightness. Take a look at the histogram and the set of data with the red box below it.

Close the previous layer of the eye, "channel" to "brightness." Take a look at the histogram and the set of data with the red box below it. and compare it to the histogram above. Can be seen, basically the same, data on the small access is calculated error.

The above is a comparison of the histogram of the entire image, below the image on the point to compare. Open the upper image of the eye, take a color point, notice the data on the information Panel.

Close the upper layer of the eye, close the top image of the eye, using the information Panel data for calculation: 0.3x238+0.59x190+0.11x144=199.34, the rounding is 199.

Let's turn the image into lab mode again. The upper layer is no longer needed, close or deleted. Open the histogram to see the underlying lightness. Note that the histogram and data, and the 10 floor of the histogram and data comparison, you can see that the difference is very large, this is not the error can be explained.

Select the Brightness channel in the channel panel, see the set color point of the data is 216, obviously not equal to the formula 0.3r+0.59g+0.11b calculated value of 199.34.

Compare Lab's Mindutu with RGB brightness chart, the difference is obvious. Therefore, the 0.3r+0.59g+0.11b should be the brightness calculation formula in RGB mode rather than the lightness calculation formula in lab mode. Have consulted Feng Xi moderator, the calculation of the brightness of the formula is very complex, this does not mention.