This series of Photoshop CS4 quick tips is designed to show some of the reasons why Photoshop a)earns its position at the top of the photo editors and b)how Photoshop actually expedites many of your image processing tasks. Cropping is a classic example. Given the huge size of images taken by most digital cameras, photofinishers have a lot of room to maneveur [8 to 16MPixels are available even from compact cameras]. And if you read photo imaging resource such as Popular Photography you will see a lot of the reviews of images turn on how well the photo was cropped. Cropping along with exposure and color corrections is essential to creating memorable images.

Yet despite this critical role, many photo editing tools have remarkably limited tools for cropping. Photoshop has steadily added features that have supercharged its cropping tool. Here are some of those cropping features:
1)darkening the image area outside the crop - this helps visualize the effectiveness of the crop;
2)allowing the crop rectangle to be rotated - so that users can straighten the image to its horizon line;
3)allow the user to enter a resize width or height - so the cropped image is reduced or expanded accordingly;
4)allows the user to specify both width and height and - so the cropped image maintains both a specific aspect ratio and also a specific size including DPI resolution. This can save buckets of editing time;
5)the perspective option allows 3D corrections - by moving the corners of the crop - another powerful feature;
6)allows the user to expand the crop into Photoshop's background/canvas - this signals you want a border using the current fill color to be added to the final crop;
7)adding a Image |Crop command that uses a current selection to define the boundaries of the crop - one of my favorites because it provides a alternative way to crop based on my selection decisions. Often I Select | Inverse and then Edit | Cut to isolate the selected image element. Another big time saver.
8)adding an Image | Trim command that crops and removes unwanted color at the edge of the image while cropping. In sum, Photoshop provides a wealth of cropping options which will be shown seen in the following demos.

Setting up the crop is vital to getting the most from the tool. Here is a screenshot just before tracing out the crop area.
I have highlighted in yellow the crop tool in the toolbox, the width setting, and the resolution setting before using the Crop tool. In this case I have chosen the crop to have a specific width [600 pixels] and the resolution to be 120 DPI after the image is cropped [Also I set the interpolation method used for resizing the image to Bicubic Sharper in theEdit | Preferences | General | Interpolation pulldown. In effect I am getting two tasks accomplished in one - cropping and then resizing the image by setting width and resolution. If you don't want any resizing done just use the Clear button to erase any resizing values. Note as well that the image needs to be straightened or leveled - the image is off-kilter or downsliding to the left. So in the next step I shall show how to straighten an image during crop using the rotate capability

Meanwhile the actual crop operation is quite simple. Just point to the upper left or lower right corner where you want the crop to begin - and with the mouse down just drag out to create your own cropping rectangle. For typical results, see the next panel, Crop Demo Cropping Example.

The image below shows a typical crop. Note that the area outside the crop is darkened.
You can control the color and opacity of this crop shading or shielding by doing two things: 1)choosing the crop shield color as highlighted in the property/options bar; and 2)adjusting the opacity setting into the 70-90% range. Note how the shield's shading emphasizes what the crop results will be. Also in this case, the crop rectangle has been tilted to straighten or level the image. Note that the volleyball nets in the backgtound are now horizontal. If you are familiar with Photoshop's image transform features, they work the same in crop mode. So when you bring the mouse cursor close to an outside edge of the crop box it changes into a curved double arrow [see upper right in our screenshot]. Just drag with the mouse pressed down to rotate the crop box up or down.

There can be a problem when you straighten out an image this way. One of the corners may go outside the image. And as we have noted, any Crop area outside the image is filled with the background color. In this specific image the upper right corner did that - it jutted out slightly into the background. So I had to use the Perspective option in the Crop tools by checking it in the Crop option/property bar and then dragging the upper right corner back into the picture [see the yellow highlight near the image's upper right corner in the screenshot]. Then turn off the Perspective option if you want to adjust the sizing of the Crop box by dragging any of the corner handles. If you want to adjust any side of the Crop bounding box, just click and drag any of the mid point handles [the small squares in the Crop marquee line] and adjust accordingly.

So now you know the essentials of Cropping [and, if you are new to Photoshop, the basics on shaping Photoshop images using Edit | Free Transform and Edit | Transform commands]. The next panel shows two specialized Crop methods the Image | Trip and Image | Crop commands.

The Trim command is used to crop away unwanted colors on the edges of an image. This situation arises often with screen captures as in the demo image below:

When you click the Image | Trip command a Trim-controlling dialog immediately appears with two choices. First, you choose what color to trim by designting the color at the top left or bottom right corner. For Photoshop, this is really Mickey Mouse. Adobe should have a eye dropper tool in the dialog as in the Image | Adjustments | Curcves command. Also Adobe should provide a color tolerance or range for the Trim command to work with. The second choice is which sides to remove the color from - the default is that all 4 sides are selected. The screen shot below shows the results:


Just as the Trim command uses color, the Crop command uses a prior selection to determine how an image is to be cropped. The Crop command is often used after isolating/selecting a figure in order to apply a new background as in the example below.

The Trim and Crop commands provide for specialized cropping needs; most users will find the Crop tool more than adequate for most cropping situations.

Cropping in photography is like editing in writing - its is the essential tool in paring down to the core of an image. Fortunately Photoshop provides a Crop tool which is not only easy to use; but also helps a PhotoFinisher decide how well a crop is going to work. As a bonus the Crop tool allows one to resize an image to the exact dimensions and DPI resolution desired. As well corrections for leveling/straightening an image or realligning perspective can be made. Finally, with the Trim and Crop commands users can crop based on color to trim/erase or based on a selection outline to crop to. In sum, I find the Cropping capabilities not only easy to use but also hard to match in other photo editing software.