Part6.Image Editing Basics

Part 6. Image Editing Basics

Task

132

2 How to Add Canvas 134

3 How to Crop an Image 136

4 How to Flip and Rotate an Image 138

5 How to Warp an Image 140

6 How to Silhouette an Image 142

7 How to Use the Healing Brush 144

It is inevitable that you will have to resize, rotate, flip, or silhouette almost every image with which you work. These basic tasks are important because you must know how to do them before you can apply more advanced processing. In addition, if you do not properly perform tasks such as silhouetting and resizing, you can destroy image resolution or create less-than-desirable results.

These preprocessing tasks or image prep tasks are fundamental skills every Photoshop user must master. Exercising these skills with speed and precision will bring a high level of consistency and quality to all your work.

You should pay special attention to resizing images safely to minimize loss of image quality. Images are made up of small building blocks called pixels; the number of pixels in an image's width and height determines the image's resolution. Consider an image that is 500 pixels high and 700 pixels wide. If you ask Photoshop to increase the image size to 700 high by 900 wide, you are asking it to add pixels. Where do these pixels come from? Photoshop makes them up, using a process called interpolation.

When adding a new pixel, Photoshop looks at the surrounding pixels to determine the value of the pixel it will add. When Photoshop interpolates an image, it can use one of five methods: Bicubic, Bicubic Smoother, Bicubic Sharper, Bilinear, and Nearest Neighbor. Select the method Photoshop uses from the Preferences dialog box by selecting Photoshop, Preferences, General. With the Bicubic methods, Photoshop looks at the pixels on all four sides as well as on all diagonals to contextualize what the new pixel's value should be. When enlarging an image, use Bicubic Smoother; when reducing an image, use Bicubic Sharper. Adobe has also left the Bicubic setting, which has always been the default quality standard, in case you'd rather keep using what you're used to. With the Bilinear method, Photoshop looks only at pixels vertically and horizontally. With the Nearest Neighbor method, Photoshop looks only from side to side. As you can imagine, the Bicubic methods deliver the highest level of quality for most photographic images, although they take the longest to process. The Nearest Neighbor method generally provides the lowest quality for photos, but it does a great job on hard-edge, graphic shapes and is also the fastest method of interpolation. •