New use of color channel in late PS

New uses for color channels

When discussing the color Range command, the reader may be surprised that the resulting selection channel image is similar to the original image. So, can the color channel be used as a selection in addition to the color value?

There is no doubt about the answer. The color channels store a wealth of selection information, for users, the full use of this information, than the choice of tools and time-consuming effort to build a constituency, often a half times.

Any color channel, including a composite channel, can be used directly as a selection. When you click on a color channel, the user can drag it to the icon below the channel palette, which loads the channel as a selection, and a new interpretation of the color level on the original color channel, which turns into more and less choices.

It's like iron in the Guan

The 1th step as shown, the image of the blue sky appears to be not enough, the whole picture appears relatively flat. If you use the "curve" command to adjust directly, it will lead to the lower mountains too dark, loss of layered sense.

Step 2nd Observe the color channel of the image individually and decide to select the blue channel as a mask for the next image adjustment. The blue channel is chosen because the blue area of the sky is brighter in the blue channel, and as a mask, the area can be greatly changed.

Drag the blue channel directly onto the icon below to load the blue channel as a selection. The ant line will appear on the screen. However, we have repeatedly stressed that at this time the ant line is a drag, will only play the role of interfering with the eyes of the operator, so, then if the direct use of image adjustment commands, it is best to press ctrl+h shortcut key to hide it.

Step 3rd If you use an adjustment layer to adjust the image (compared to using the image Adjustment command directly, using an adjustment layer is a more advanced method of image adjustment, so you don't have to hide the ant line because the selection on the screen changes to a mask, and the ant line disappears after the adjustment layer.

Select the Curves command under new adjustment layer on the Layer menu, and the Curve dialog box appears, adjusting the curve as shown, which darkens the image.

Because of the masking protection, the darkened area of the image is the smallest.

You can pause the cursor over a layer mask, right-click, and select the Deactivate layer Mask command, which is the effect of a curve setting without using a layer mask. As the reader can see, the peaks are almost completely obliterated in the darkness.

Copy and transform a color channel

On more occasions, it is not appropriate to load the color channel directly as a constituency, because the clothes may not fit, and need to be cut with tools or commands to suit the choice.

For example, using the tools in the toolbox is difficult to select from a dandelion as shown in the picture. With the color Range command, it's not difficult to do this. Using the channel provided by the color channel, still can achieve the goal.

The 1th step is to carefully observe each color channel, to find the most able to separate the object from the background color channel (sometimes the most distinguishing between the foreground and the background channel is not necessarily the most contrast channel), click the right mouse button, copy the "Blue" channel to "Blue Copy" channel.

Directly in the color channel modification is unfamiliar to the channel operation of the user often make mistakes, directly modify the color channel will cause the image color changes.

The channel is not mysterious, it is a grayscale image, so the modification of the channel is essentially an image processing work. Various methods and tools of image processing are suitable for processing channel images.

Step 2nd uses the Levels command for the blue copy channel.

Select the "image → adjust" menu under the "Level" command, the user can set the Black field by the way the complex background to black and retain the dandelion's slender fuzz.

The 3rd Step Dandelion Center in the middle of the heart need to keep. The user can open the color channel's eye icon to determine the area that needs to be modified on the blue Copy channel and select the Eraser tool to erase the dandelion's middle area.

Layers and channels have two properties, that is, display status and edit state. Layers or channels that are in the editing state are not necessarily displayed (such as layer masks), and layers or channels that are in the display state are not necessarily being edited.

Close the color channel and observe the modified effect.

Step 4th loads the blue copy channel as a selection, opens the Layer palette, and returns to the background layer. Use the Copy command on the Edit menu to copy the image within the selection to the Clipboard.

The 5th step we prepared another image called "Cactus", ready to a deceitful act.

Step 6th Use the Paste command to paste the content you just copied to the Clipboard as Layer 1, and use the transform command to zoom the dandelion to the appropriate size and move to the appropriate location.

"Layer 1" can be temporarily hidden, wiping off the original flowers on the cactus. This kind of hidden and displayed operation is very common when manipulating layers or channels.

After some trivial modifications, the dandelion's umbrella was transplanted to the cactus.

From contour selection to range selection

For this black-and-white selection shown in Figure 1.101, no matter how complex the shape, there are only two colors that make up the image: Black and white. This choice is often referred to as an "outline constituency."

For an outline constituency, the ant line can accurately reflect the range of the selection.

A selection of black, white and gray continuous color bands, as shown in the figure, is called a range selection.

For this type of constituency, the ant line indicates a dividing line of 50% grayscale (128 levels), but it does not mean that regions with brightness greater than 128 levels are selected, and regions with a luminance less than 128 levels are not selected. In a sense, the ant line to the range constituency is not so much helpful as causing confusion. It does not help the operator to judge the scope of the constituency.

In future studies, the reader will also be exposed to a constituency called the middle tune. If you load this selection from the channel, the Ant line will not be visible on the screen. Photoshop prompts the operator with a warning: no pixels are greater than 50% selections, and the selection edges will not be visible.

It is not so much the "constituency is not visible" that the scope of the constituency is more precise than the boundary. 50% Choose what can be indicated? The choice of less than 50% remains the choice.

So at this point, the operator should give up the simple and stiff thought of the ant line indicating the boundaries of the selection. In order to more accurately observe and determine the range and selection of the selection, users should often open the Channel palette, to in-depth observation of each channel image.

The change of the choice idea

From the contour constituency to the range selection, the reader will undergo a difficult shift in thinking. The deeper the dependency on the Contour constituency (or the selection tool in the toolbox), the longer and more painful the transition process. This is the first hurdle that users learn about Photoshop.

To help readers successfully cross this hurdle, we use some examples of everyday life to make a few metaphors.

① Learn to write calligraphy early, there is a "alphabet" practice. Students practice the bridge differences structure and brushwork skills of Chinese characters by tracing the fonts printed on the alphabet with dotted lines. These dashes can be seen as Ant line lines. In a certain period, we must learn to get rid of the limit of the dotted line.

② if carefully observed, the children's graffiti is always pure black and white color. This is related to their simple thinking: black or white, not good or bad, not without. This is in line with the idea that the contour constituencies instill in Photoshop users. However, when they grow to a certain age and realize the existence of ash, their paintings begin to draw into the sketch stage.

Category:

• PS Getting Started Tutorial
• PS Post-processing tutorial