Scanning and Manipulation Tools in Adobe Photoshop Basics
Color And Contrast Adjustment
To adjust Brightness and Contrast, use “Image…Adjust…Levels” in which you see a histogram of your image. Adjust the black, white and gray “Input” triangles to change the contrast and brightness of your image. Moving the black triangle toward the right will darken the image, moving the white triangle toward the left will brighten the image, and the gray triangle will adjust contrast. This method provides much more control than the “Brightness/Contrast” method.
To perform color adjustments, try “Image…Adjust…Hue/Saturation” or “Image…Adjust…Color Balance.”
TIP: Increasing “ Hue” (moving triangle to right) helps offset the pinkness of an old slide.
More sophisticated adjustments can be performed using “Image…Adjust…Curves.” Here you are given a color information graph. Place multiple points on the graph to increase the brightness of dark pixels and decrease the brightness of bright pixels.
TIP: You can adjust Red, Green and Blue together or individually in both “Levels” and “Curves.” Hold down the “RGB” bar to select an individual color channel.
To reduce an image to only use 256 colors:
Select Indexed Color from the Mode menu.
Select 8 bits/pixel in the Resolution area.
Select Adaptive in the Palette area.
Select Diffusion from the Dither area.
Click the OK button.
To reduce an image to only use 256 grays:
Select Grayscale from the Mode menu.
Click OK to verify.
To reduce an image to only use black and white:
Select Grayscale from the Mode menu
Select Bitmap from the Mode menu
Set the number for Output in the Resolution section to match the number for Input displayed above the Output box.
If the image is photographic, then choose Diffusion Dither in the Method area.
If the image is a line drawing, or logo, choose 50% Threshold. Click the OK button.
Removing Dust And Scratches Using the Rubber Stamp tool
First enlarge the dirty area.
Hold down the Option key and click once on a spot which you would like to sample.
Now holding down the mouse button use the cursor like a paintbrush to apply the sampled area to your target spot.
You can also try “Filter…Despeckle.”
Sharpening Your Image
Sometimes images lose their crispness when scanned. To sharpen the image, select “Filter…Sharpen…Unsharp Mask.” The other “Filter…Sharpen” choices offer shortcuts, but at the expense of control. “Unsharp Mask” allows you to specify how much you want your image Sharpened. We recommend a “Radius” of .5 and a “Threshold” of 1. The amount will vary with each image. Radius is how many pixels should be considered together; and threshold is how different pixels have to be to be sharpened.
Saving The Image As A GIF
For web design the GIF image format has the advantage of having a very small file size, thus it loads faster than a JPEG file. In order to save an image as a GIF, choose “File…Export…GIF89a Export.” A new GIF file with 256 colors and a new name will be saved to the hard drive and your current file will be left alone. If you continue to make changes to the original image, remember to export it again when you are finished.