Basic Image Editing

About Image Editing

Photoshop provides numerous powerful tools for working with images. This section describes key tools for basic image editing. The next section (More Image Editing) describes some additional image editing features.

Keep in mind the following when editing images:

It is always a good idea to keep your original image as a backup and work on a copy, in case you make a mistake and want to start over. (If you want to go back to the file as it was when you opened it, choose File>Revert. You can also go back to a previous state of your image by using the History palette.)
If you have selected an area (using the selection tools, described in More Image Editing), adjustments you make affect only the selected area. Otherwise most adjustments affect all the pixels in the image.
If your image has multiple layers, adjustments you make generally affect only the current layer (layers are described in More Image Editing). (The exception to this is adjustment layers).

Cropping Images

Cropping and Straightening Images

If you are going to want to crop your image, it is usually a good idea to do this at an early stage, before you do a lot of other editing with other tools. To crop an image:

1. Choose the Crop tool () in the toolbox. Then click and drag across the image. An outline will appear that shows you the area to be cropped.

2. Adjust the area to be cropped by using handles on the edges of the image.

Note: If you move the cursor just outside of one of the corner handles, it turns into a curved cursor, which then allows you change the alignment of the selected area. This is useful, for example, to correct a scan of a picture that was in a crooked position on the scanner.

3. Press Enter to crop or Escape to cancel.

RemovingImperfections

Using the Clone tool

The clone tool ( ), also called the rubber stamp, allows you to remove imperfections such as dust and scratches by covering them with samples of nearby pixels. For best results, zoom in close and use a small brush.

1. Zoom in close to the area you want to edit.

2. Choose the clone tool, and make sure "aligned" is checked in the Options bar.

3. In the options bar, choose a brush size (this determines the size of the sample). The cursor shows the size of the brush, as shown below. The circle is the cursor (brush).

(Note: if the cursor doesn't show the brush size, go to Edit>Preferences>Display & Cursors, and choose Brush Size for Painting Cursors.)

4. Alt-click to define initial source point (sample). In the above example, I Alt-clicked where the cursor is shown.

5. Move the cursor over the area you want to cover, and click to cover it with the sample. In the following example, I moved the cursor slightly down and to the left to cover several white specks. You can see that the imperfection has been removed (there is a slight blemish where the clone tool was applied, but it is a vast improvement).

Using the Healing Brush Tool

The steps for using the healing brush tool ( ) are the same as for the clone tool. The healing brush attempts to take the texture from the sample without affecting the brightness of the area to which it is applied. In some cases this is more effective than the clone tool. The following is shows the same correction as above, only this time done with the healing brush tool. The blemish appears to be somewhat less noticeable.

Adjusting contrast

The Levels command is a very good tool for adjusting image contrast and tonality. Choose Image>Adjust>Levels, and the Levels dialog box appears. It displays a histogram of the brightness values of the pixels in your image. There are two sets of sliders (triangles): input levels and output levels. For most editing tasks, use the input levels sliders (the three triangles just below the histogram):

To increase contrast (create more dark and light pixels): Move the left and right sliders toward the middle.
To adjust the midtones: Move the middle input levels slider to the left to lighten midtones, and move the middle slider to the right to darken the midtones.
Keep the Preview box checked in order to see the effects of moving the sliders on your image.
To make the adjustment, click OK. To cancel it, click Cancel.

In the above example, the brightness values of the image are fairly well distributed, with more dark pixels than light pixels, due to the dark areas (water) in the image. But there are few (if any) pixels that are completely white or black. We can change this and increase the contrast of this image by moving the left and right sliders a little toward the middle, as shown below.

Because the Preview box in the layers palette is checked, we can see the result on our image as we adjust the sliders. The image now has more contrast (is less "flat") than before, which in most cases is an improvement.

Note: In the above example, the Levels dialog box Channel popup menu is set to the default of RGB, which means the histogram represents a combination of all of the channels (Red, Green, and Blue light) in the image. You can use Levels on an individual channel, which may be a good idea in some cases. However, because you would then be adjusting the brightness values for only one color channel, this is likely to change the color balance of the image. (To fix this problem, consider using Auto Color, described below.)

An even distribution of pixels is not always desirable. For example, the following is an photograph of something dark, and the photographer probably wants the image to be dark as well. In this case there may be no need to make an adjustment in the Levels dialog box.

If, on the other hand, you were taking pictures outside on a snowy day, you would probably expect (and want) the Levels dialog box to show a majority of the pixels on the right side of the histogram.

Photoshop provides other options for adjusting contrast. Image>Adjustments>Brightness/Contrast is the simplest tool, but is not nearly as effective as Levels. Image>Adjustments>Curves is more sophisticated than Levels (but also more difficult to use). For many purposes, Levels provides a good combination of power and ease of use for adjusting image tonality.

Color Correction

Photoshop provides several color correction tools, and color correction is a complex topic. In the following discussion we consider Auto Color and the Photo Filters, both of which are easy to use and effective in many situations.

Auto Color

Photoshop's Auto Color command attempts to color correct images automatically by analyzing the highlights, shadows, and midtones of each channel. You can choose Image>Adjustments>Auto Color to try the Auto Color command and see if you like the results.

Alternatively, you can get to the Auto Color options by clicking the Options button within the Levels dialog box, as shown below. This method has an advantage of allowing you set different options, and it is interactive (the effects of different options are immediately visible in the image while the dialog box is still open).

Autocolor

Ben Willmore suggests decreasing the value for Highlight Clip if highlights seem to be getting blown out in your images. If you click the Save as Defaults checkbox, the settings become the defaults and are applied whenever your choose Image>Adjustments>Auto Color.

Photo Filters

One way to correct a color cast is to choose Image>Adjustments>Photo Filters. The following dialog box appears:

Photo Filter

For example, the above photo filter settings affected the image as shown below. Because the Photo Filter dialog box has a preview box, you can see the effect settings will have on the image. Increasing the density setting will increase the effect of the filter.

The above are just two of several color correction options provided by Photoshop. Another option you may want to consider is Image>Adjustments>Hue/Saturation. Hue/Saturation allows you to simultaneously adjust all the hues in your image by changing their positions on the color wheel (as opposed to tinting everything in the direction of one hue). You can also use Hue / Saturation to change the saturation of color in your image.

Sharpening

Use Filter>Sharpen>Unsharp Mask to sharpen an image. In the dialog box that appears, keep the preview box checked. This allows you to see the effects of different settings.

Amount -- How much sharpening is applied. Consider using a value between 50% and 150% for typical images.

Radius -- The number of pixels affected around edges. Consider using a value between 0.2 and 2.0. (Deke McClelland recommends using 0.1 of radius for every 15 ppi in the image. For example, for an 150 ppi image, you could use a radius value of 1; for 300 ppi, you could use a radius of 2.)

Threshold -- Defines what brightness difference qualifies as an edge (0 is default, sharpens all pixels). Consider using a value somewhere between 1and 5 (for Threshold, the higher the value, the less pronounced the sharpening effect).

Note: Sharpening is more an art than a science, and is somewhat subjective. The above settings are only suggestions. For best results, you need to look at the particular image and figure out for yourself what looks best! To get the best idea of the effect your settings will have, make sure that you are viewing the image at 100% magnification, and be sure to keep the Preview box checked in the Unsharp Mask dialog box .