Photoshop Image Color Leveling technology

This blog post briefly introduces the technology of using Photoshop to color the image data

Images typically have IMG and TIF two kinds. General images if opened in PS, the coordinate information is lost. In the process of uniform color processing, the common practice is to first export the coordinate information, and then use PS to adjust the lust, and then restore the coordinate information. My brother recommended me to use the GlobalMapper12 software, saying that this software can save coordinate information. But I have not tried.

School of Remote Sensing Information Engineering, Wuhan University a teacher developed a plugin that was developed based on Photoshop CS 4. This plugin allows images to be opened in PS without losing coordinate information. However, this software has a flaw, if the TIF format image more than 2G, it will not be loaded. We can first use Erdas to convert the TIF format image to IMG and then open it with Photoshop (I've opened a 10G-size TIF image with Photoshop CS 6).

After you open the image in Photoshop, there are two ways to adjust the color of the image: the first is directly in the "image-and-adjust curve adjustment", the use of the way the menu adjustment is irreversible, less convenient to control, and the second is the use of layer management method. This approach is described in more detail below:

1 Click to create a new curve layer, and when the histogram appears, pull the peak

A graph layer appears in the layer list and the Histogram window opens

2 adjusting the color channel of the image

Color Channel A total of four options, namely: RGB, red, green, blue.

A directly pull the histogram in the straight line, you can adjust the image gray value, upward is more white, downward increase in gray.

b Select the red channel, pull up, increase the red weight, pull down, the red weight is reduced. The blue and green channels are similar in approach.

C Pull direction, in addition to the line form, there is the S-type, S-shaped curve, can sharpen the image, enhance contrast. If (after shrinking, the effect will be a little more obvious)

Original image

After S curve

The image in the D example, red, needs to be evenly colored to the green, the concrete step is: with red channel, reduce red, and then green channel, enhance the green.

3 Adjusting the saturation level

To open a saturation layer:

Original image

After adjustment

4 Coordinate information Save

At the end of processing, an IMG file with coordinate information can be saved using the Wuhan University plugin above. If you drag into ArcGIS and find no spatial reference information, there are two ways to resolve this issue.

1. Convert the file to a TIF file and copy the names of the Tfw,tif.aux.xml and TIF.OVR three files to the TIF file directory and make the file names of the four files consistent. This allows you to save the coordinate information. Such as:

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1. If the coordinate information is correct, but there is no spatial reference coordinate system, you can define the coordinate system directly in ArcGIS.

Another: If your machine can directly open 10G or more in TIF or img format images, you can also try to evenly color, perhaps the coordinate information will not be lost.

Photoshop Image Color Leveling technology