Chapter 12 CS4
Download Materials for Chapter 12
Exercise 1 From digital input to web ready
1. Download and open orbitzad1.jpg from the wiki, or get any image from your digital camera or scanner.
2. If you followed the exercises in Chapters 8 and 9, you should be comfortable changing the tonal range and color of this image. Adjust the tonal range and color to your liking by creating adjustment layers.
3. Save this file as a master copy by choosing Save As from the file menu, adding “_master” to the file name and then choosing PSD as the file format. We saved ours as orbitz_master.psd.
4. The image from the wiki is straight off a 7-megapixel digital camera, and is much larger than can be displayed on a web site. Choose Image > Image Size and notice the size of your image in pixels. Check the boxes next to Resample Image and Constrain Proportions, then change the pixel dimensions at the top of the box so the largest dimension is no larger than 1600px. If your image is less than 1600px on its long side, you can use the Cancel button to close this dialog box without making any changes.
Tip: Monitors generally have display settings such as 1280 by 800 or 1024 by 768 pixels. A file whose longest side is 1600px is likely more than big enough to fill a web browser window on any monitor. The only measurement unit relevant to us in this exercise is pixels, as the image will be shown on a platform that also uses pixels.
5. Add an unsharp mask (Filter > Sharpen > Unsharp Mask). Make sure you have the image layer selected, and not one of the adjustment layers. We used the following settings for the Orbitz ad photo: Amount, 25%; Radius, .6px; Threshold 0 levels. Your image may require different settings.
6. Choose File > Save for Web & Devices. Photoshop and Illustrator share this save for web interface. It allows you to compress your images, flatten layers, and prepare an image for the web.
7. The Save for Web & Devices dialog has several important parameters to set. The most important parameter is the Optimized file format. As a general rule, photographic images and other images with more than 256 colors are saved as JPEGs. Graphic images — images with few colors such as logos and line art — are saved as GIFs or PNGs. Since this image is a photograph, select JPEG from the Format pull-down menu.
8. Select the default quality of High, or 60. Saving a file for the web compresses the saved image into a smaller file size by removing color information and pixel detail. This is called lossy compression.
Note: The human eye cannot detect image compression artifacts if used with a light touch and when the image is viewed on a computer screen. Compression runs from Low to Maximum, and corresponds to a numerical range from 0 to 100. Zero is a very low quality, where you will definitely be able to notice the loss of quality in the image, while the maximum 100 level, although still having had image data thrown away, shows no visible decline in quality. The trade-off is that more compression creates a smaller file. Weigh your needs for file size against your perception of image quality to decide what level of compression to use.
9. Click on the 2-Up tab to show the original image in its native format next to the compressed image. Notice that the original image has a file size of 5.49MB, and the file size of the optimized image is 368KB. The compressed image is 15% of the original file size. This is important because the smaller the file size is, the faster the image will download as part of a web page.
Tip: The zoom and hand tools allow you to get a closer look at the image and move to important details.
10. Reduce the quality to Low, or 10. Notice how much detail is lost. Visible compression artifacts are introduced into the image. Our file size is much smaller at 85KB, but we have compromised too much image quality for the sake of the smaller file size.
Tip: If your settings disappear, click on the lower preview window.
11. Return the Compression quality setting to High, and click the Save button.
12. Name your file with an underscore and the word “web” like we did when we named ours orbitzad_web.jpg, and save it to the Desktop. Remember web standards when naming files: only use lowercase alphanumerics, underscores, and dashes.
13. Close and do not save the orbitz_master.psd that is currently open. (We saved the master file in Step 3 before scaling the image and we don’t want to save this smaller version over it.)
Watch Out: When you open and file and resize it, it is no longer the master file. This may seem confusing, but it is a situation you will commonly experience when maintaining master files and resized web ready files. There’s nothing stopping you from using Save As to save your scaled-down master file as well, but it’s probably overkill and could mislead you later into believing it’s the largest version you have.
14.Open the JPEG you just saved for web (ours is orbitzad_web.jpg) in Photoshop, and notice that there are no adjustment layers. By saving for the web, we flattened the image.