Adjusting Scanner Settings
Scanner software has many options that enable you to determine how much image information is downloaded to your computer. To access all the software options, preview and scan a photo into your computer. This section will show you how to choose a resolution for scanning photos into Photoshop Elements.
If you're using a flatbed scanner, place a photo or a piece of paper with text or graphics face down on the glass surface of the scanner. If you're using another type of scanner, insert a scannable document into the scanner device. Some scanners, such as the Epson 640U, automatically scan and choose the settings for you. The HP Photo Smart scanner starts scanning when you insert a photo, filmstrip, or slide (see Figure 3.4). Other scanners require you to click a button in the work area to start the scan.
Figure 3.4 Create a preview scan to get a rough idea of how the scanner software sees the scanned photo.
What Is the Best Resolution for Scanning?
Most scanners are capable of scanning within a limited range of resolutions. Assuming you have a more recent scanner capable of scanning up to 2400 dpi, try scanning an image at 600 dpi. Then compare that scan to the same image scanned at 720, 1200, or 2400 dpi. Usually the higher dpi setting will produce the sharpest scanned image. Save the highest-quality image to your hard drive.
If you cannot see a difference between the resulting images, save each one to your hard drive. Then compare the file size of each scan. Use the Zoom tool to determine how much more image information is added to the higher-resolution images. If the 600 dpi scan looks great and creates the smallest file size of the scanned image, you might want to consider working with this setting when you scan other images.
Choosing a Resolution
If you want to scan several images into the computer with the same resolution setting, you can choose the resolution and scanner settings for one photo and scan the rest without making any changes. However, if you have a diverse set of colors, or old and new photos, you might want to set aside a big chunk of time if you want to get the best results for each scanned image.
Consider the following issues when trying to set the optimal resolution for scanned images:
What kind of image are you trying to scan? Consider the size of the image, and decide which resolution would be able to capture the most detail without creating an unusually large file.
How many colors does the image have? If you're scanning a color image, you might need to configure the scanner software to capture thousands of colors instead of 256. On the other hand, you can see what happens if you scan in a color image as a grayscale or black-and-white image.
What is the highest non-interpolated resolution supported by the scanner? Some scanners work with bundled software to capture higher resolutions than the scanner hardware is capable of creating. You might want to compare the software-enhanced, high-resolution scans with the same image scanned at a lower resolution without the aid of the software interpolator.
Does the computer have any display limitations that might limit your ability to view beyond a certain resolution? You might need to change your computer monitor's settings to display more colors if you want to see as much of the scanner output as possible. The computer's performance can slow down if you set it to display 24-bit color, compared to 256, or 16-bit color. The more colors the monitor has to display, the more processing power is required from the computer.
Choose a resolution in the scanner software window. Look for a resolution setting that enables you to set the spi or dpi of the image. Some software breaks down the resolution settings into horizontal and vertical resolution settings. The horizontal resolution affects the optics in the scan bar, and the vertical resolution affects how far the bar will move as it scans each line of the image.
Adjusting the Color Depth and Scan Area
The number of colors, or color depth, of the scanned image affects the quality of the resulting captured image. Most scanners automatically scan an image in color, even if the image has no color. You can adjust the software settings to scan a black-and-white image if you like. The scanner does not have any sensors built into its optical array that can distinguish a color image from a black-and-white one; it simply captures the image placed on the glass.
Although most scanners rely on the CCD and scanner hardware to determine how many colors can be scanned, each uses its own software and terminology to describe color depth. For example, the CanoScan N1220U uses the term Color Mode to describe its color depth settings: Black and White, Grayscale, Color (Photos), Color (Documents), or Text Enhanced. The Epson 640U uses the term Image Type to describe its color depth options: Color Photo, Color Document, Black & White Photo, or Black & White Document.
Be sure to adjust the color settings for your computer's operating system and monitor before you scan an image. Both Windows and Mac OS enable you to customize the resolution or desktop size. You also can set the color depth, or number of colors that can be displayed onscreen. If you want to learn more about how to work with color, see Chapter 7, "Photoshop Elements and Color."
The important thing to remember here is that you want to pick a color depth that matches the photo placed on the scanner. For example, if you're scanning a black-and-white image, choose a grayscale or black-and-white color depth. If you're not sure which color depth to choose, choose a setting as close to 16- or 24-bit color as possible. The higher the color depth value, the more color data will be captured when the image is scanned. For example, scanning an image at 24 bits will capture more color information than scanning at 16 bits.
Experiment with different color depth settings with different kinds of images. You can scan photos, line art, sketches, text, two-color images, or full-color images at different color depth settings to see how your scanner reacts to different capture modes. I capture almost all my images in color, and remove or add colors with Photoshop Elements.
The resolution setting also affects how the image will be scanned. The higher the resolution, the more color information the scanner will try to capture. If you're not sure at what resolution to start scanning an image, choose 600 dpi. Scan and save the image, and then change the resolution to 1200 or 2400 dpi and save this second image. Open each image and place them side-by-side on your desktop. If you cannot see any improvement in the 1200 or 2400 dpi image, you might want to continue to scan additional images at 600 dpi. However, if you plan to edit images, the higher resolution scan will enable you to do more precise image editing than an image scanned at a lower resolution.
Comparing SPI to PPI
Scanners capture images using the measurement of samples per inch (spi). However, your computer monitor displays an image in pixels, or 72 pixels per inch. You might wonder whether a sample and a pixel are the same size.
Sadly, the answer is no, they are not the same size. In fact, there isn't an easy way to compare the quality of a scanned image to an image viewed on your computer monitor. The final results depend on the output of your printer, the settings and capabilities of your computer monitor, and your ability to choose the software settings that create the best possible images.
Previewing and Setting Up for the Scan
To create a preview of an image, before you actually scan it into your computer, click the Preview Scan or Preview button in the scanner software window. Don't be surprised if your scanner does not have a preview option available. If the scanner software doesn't support a preview mode, click the Scan button and wait for the image to be scanned into the work area.
Some scanner applications, such as the Epson 640U, enable you to let the scanner do all the thinking for you with a full-service auto-scan feature. You might need to turn or flip the image on the scanner bed if you want to straighten the scanned image. If you want to avoid creating unnecessary scans, check to see whether the scanner you are planning to buy includes a preview option in its software package.
After you have created the preview scan, you can apply the selection tools to choose the specific area you want to scan into the work area (see Figure 3.5). Reducing the area being scanned reduces the amount of time you must wait for the scanner to complete its job.
Figure 3.5 If the scanner software provides tools, you can select the area you want to scan.
After the scanned image is captured and viewable in the work area (see Figure 3.6), you can save it to your hard drive. Choose Save from the File menu, and then type a name for the image file and save it to your hard drive. Now you can experiment with the image by applying one of the tools in the Toolbox, or add a new layer to the image file if you don't want to make any permanent changes to the original image.
Figure 3.6 The resulting file contains the image you selected in the scanner software window.
Photoshop Elements opens scanned images in RGB mode, enabling you to work with red, green, and blue color information. You can apply any menu command or tool to any part of an image in RGB mode. To find out more about the image modes in Photoshop Elements, go to Chapter 7.
Shouldn't This Look Prettier?
Scanners might be able to create luscious 36-bit and 48-bit color images, but most monitors are capable of displaying 24-bit color, or millions of colors. You might not be able to see the additional colors captured by the scanner, but Photoshop Elements enables you to work with all the color information captured by the scanner. You will see the difference when you edit or print the image.