A guide to photo processing

Whether you get your photos from a scanner, digital camera, or a third party, they almost always require some form of manipulation before final output. Here's a start-to-finish guide to common image processing tasks. Although not every picture will require every one of these steps, they should be performed in the order presented for best results.

Step 1: Save a Copy
Before anything else, it's always a good idea to save a copy of your image.

Step 2: Rotate
Not every image will require rotation, but if you often use your digital camera in portrait orientation, if the camera was tilted, or if the images were scanned at an odd angle, they will need to be rotated. This is also the time to correct distorted perspective, using your software's skew, transformation, or distortion tools.

Step 3: Crop
Cropping is one of the simplest things you can do to enhance a photo, yet many people neglect this step. By cropping your photos, you can remove unnecessary and potentially distracting elements so viewers will be able to focus on the important parts of your picture. In addition, cropping can significantly reduce file size, which is important for photos you intend to post on the Web or send via email. The order of this step isn't critical, but unless you have a good reason not to, it makes sense to crop early in the process for a couple of reasons: First, A smaller image requires less of your system's resources and can cut down on processing time. Secondly, many problem areas in a picture can simply be eliminated by cropping them out.

Step 4: Correct Color and Tone
Now is the time to examine the overall color and tone of your image and adjust for color casts, underexposure, overexposure, and so on. It's important to get color and tone corrected before moving on to restoration, retouching and other types of image enhancements. This is best done through your software's levels, curves, histogram, or tone map adjustment commands. Avoid using brightness/contrast, and hue/saturation adjustments for these types of corrections because they are "flat" adjustments that will destroy the overall tonal range in your photos.

Step 5: Repair and Restore
Now that you have accurate color and tone, you can focus on the flaws in the image that may need to be repaired. This includes removing unwanted moiré patterns, dust, scratches, tears, wrinkles, spots, and noise.

After all repairs have been made, you may discover other cosmetic flaws in the image that need retouching. This can include removing distracting elements, revealing obscured objects, smoothing skin tone, reducing red eye, removing wrinkles and blemishes, perhaps even replacing entire objects.

Step 7: Save Your Working File
Now is a good time to do a final save of your corrected, restored, and retouched photo. If you will be using the image in another project you can come back to this file at a later time. The following steps are specific to the requirements of final output and will be saved under a new file name in step 10.

Step 8: Resize or Resample
Chances are, your image is not going to be the ideal size for your final output. You will need to use your software's resize or resample command to adjust the size and resolution. If your image is going to be printed, you will need to set the resolution somewhere between 150-300 ppi and enter the desired print dimensions. If your image is intended for the Web or multimedia, you will want to use a resolution of 72 ppi and enter the desired pixel dimensions.

Step 9: Unsharp Mask
Many times, as you adjust the size of an image it will need to be resampled. This resampling always results in some softness or blurriness. In addition, other image processing tasks such as rotating and retouching can soften the image. Therefore, you always want to apply Unsharp Mask as the last step before saving for final output. This filter is standard in most popular image editors and produces better results than the simpler Sharpen command. When sharpening, be sure to view your image at 100% magnification or actual pixels. Other magnifications will not give you an accurate preview of the results.

Step 10: Save a Copy for Final Output
At this point you are ready to save a copy of your file in the format required for final output. For photos you'll be posting on the Web or sending by email, you will probably want to use JPEG format. For photos being used in a printed project, TIFF is commonly used. If storage space is a concern, you can use a high-quality JPEG for a much smaller file size compared to TIFF. For images intended for multimedia or other types of screen display, you may need GIF or PNG although TIFF and JPEG may also be used.