Multimedia Production Tools

How to Scan for Multimedia

Launch Adobe Photoshop.

Choose Acquire from under the File pull-down menu. If your scanner is a TWAIN-compatible scanner choose Twain and you will see your scanner software appear.

This will bring up the scanning software's settings dialog box. You basically want to scan in 24-bit RGB mode at a resolution of 300 dpi. You can normally change the size of the scan area by dragging the outlined box in the preview screen. Below are some of the standard options you might see:

Mode: Color RGB (24-bit or 48-bit)

Original: Reflective (transparency for slides, or negative)

Input: 300 ppi

Scale to: 100%

Range: Automatic

Tone Curve: None

Descreen: None (could be set if moiré pattern a problem, magazine, newspaper quality, etc.)

Sharpness: None (normally you do all post processing in Photoshop)

Settings: Current, or you can use "My Personal Settings" - a file which you can set and save.

Remember to scan at 300 dpi (no less, you need the data for resizing) at 100%.

Basic Photoshop Cleanup Operations for Scans

In Photoshop, use the Marquee tool to select the area of the scan you wish to keep (cropping out extraneous information). Select Crop under the Image pull-down menu.

Select the Auto Levels command under the Image pull-down menu, under the Adjust sub-menu.

If Auto Levels does not color correct to your satisfaction (making the whites pure white and the blacks pure black), select the Levels command under the Image pull-down menu, under the Adjust sub-menu.

Within the Levels dialog box move the middle slider to the left to increase the gamma level. This will lighten the image without loss of data. Click OK when you are satisfied. If you wish to reset the Levels dialog box without hitting the Cancel button, you can option-click the Cancel button to display the Reset button. This saves lots of time when you are experimenting.

Next you need to sharpen your scan using the Unsharp Mask filter from under the Filters menu and the Sharpen sub-menu. All scanned images need some sharpening, even those scanned on high-end drum scanners. The Unsharp Mask filter works best set at the following settings:

Amount: 70%
Radius: 1.0 pixels
Threshold: 0 levels

What does Unsharp Mask mean? Unsharp masking is an unusual term for a sharpening technique, but that's what this Photoshop filter does. The name comes from the conventional method used to sharpen images on film — a blurred positive film is sandwiched with a sharp negative film and the result is shot on high-contrast photographic paper. The resulting lighter and darker line on each side of an edge give the edge added emphasis. Photoshop offers three settings for its Unsharp Mask filter:

Amount. The Amount determines how much the contrast of pixels is increased. For high resolution images, an amount between 150% and 200% is recommended. For screen resolution images, an amount of 50% to 70% is typical.

Radius. This determines the number of pixels surrounding the edge pixels that will be affected by the sharpening. For high resolution images, a Radius of between 1 and 2 is recommended. For screen resolution, a Radius of 1 pixels is typical.

Threshold. This determines how different the brightness values between two pixels must be before they are considered edge pixels and are sharpened by the filter. For images with fleshtones recommended Threshold values are between 2 and 20. The default Threshold value of 0 sharpens all pixels in the image.

If you find that applying the Unsharp Mask filter makes already bright colors in your image appear overly saturated, convert the image to Lab Mode and apply the Unsharp Mask filter to the L channel only. This will sharpen the image without affecting the color components. Be careful not to oversharpen your image.
Below are some Unsharp Mask settings you can experiment with:

Amount = 25 Amount = 120 Amount = 200
Radius = 1 Radius = 1 Radius = 2
Threshold = 5 Threshold = 5 Threshold = 20

Now save your 300 dpi file as a Photoshop file with the extension ".psd". Files saved with this extension can be read on a Macintosh or a PC.

If you need to resize your photo to a specific size, say 640 pixel width at 72 dpi for the computer screen, this can be done by selecting the Image Size command under the Image pull-down menu. This brings up the following dialog box:

In this dialog box, type 72 in the resolution box, and set your final image size to 640 Width or 480 Height. Always keep the Constrain Proportions button at the bottom of the dialog box checked on. Otherwise your photo will not retain its true proportions.

For the time being leave your photo in 24-bit RGB mode. We will later convert the 24-bit image to 8-bit Adaptive palette mode using for use in Director or other multimedia applications. If you were to change from RGB Mode to Indexed color this would be done by selecting the Indexed Color command under the Mode pull-down menu. Click 8-bit under Resolution, then click Adaptive under Palette, then click Diffusion under Dither as shown below. Then click OK. Review the Mode menu information given below if you wish to understand the different Mode options.

If you wish you keep your image at 24-bit, millions of colors for the web, you should now save it as a JPEG file experimenting with the right compression level to balance between a good quality image and one which will load at a reasonable rate.

Otherwise, for CD-ROM or other multimedia presentation you will need to convert the photo from 24-bit RGB mode to 8-bit 256-color System palette mode for use with Director. To do this select Mode under the Image pull-down menu. Then select Indexed Color. Click 8-bit under Color Depth, then select System (Macintosh) under Palette, then select Diffusion under Dither as shown below. Then click OK.

To turn your 24-bit RGB image into a Web palette GIF (8-bit or less) select Mode under the Image pull-down menu. Then select Indexed Color. Select Web under Palette, Other under Color Depth, then select Diffusion under Dither as shown below. The exact number of colors needed to display this image will be displayed. Then click OK. To reduce colors even more, return to RGB mode by selecting Mode under the Image pull-down menu. Then select RGB. Next, select Indexed Color. Select Web under Palette, Other under Color Depth, then select Diffusion under Dither as shown below. The exact number of colors may be somewhat reduced thus reducing your file size. This step calls for experimentation.

Now you are ready to save your scan in a PICT file format for importing into Director or GIF or JPEG for the Web. Under the File pull-down menu, select the Save command. Choose the file format by holding down the Format box. Select PICT and name your file using the extension ".PCT" so that others will know what format the file was saved in. Click Save.

Use the extension ".GIF" for GIF files or ".JPG" for JPEG files for the Web.

Photoshop Color Modes

Definition. Image files contain information that define the color that makes up the image. This information determines the color mode of an image. Color modes are based on established models for describing and reproducing color. The Photoshop Mode change operation lets you convert between different image types. For example, a Mode change operation might be used to change a color photograph into a grayscale or black and white image.

Bitmap mode. Bitmap images consist of only two colors: black and white. Converting a color or grayscale image into a bitmap will force Photoshop to reduce the number of colors in the original image to two — black or white. Fortunately, there are a some options to control how Photoshop makes the conversion.

Halftone Screen lets you convert the pixels in a grayscale image to simulated halftone dots. You can save halftone screen settings and reuse them with other images.

50% Threshold converts every pixel of the original image to black or white by determining the brightness of each pixel, and turning those pixels whose values are less than 50 percent to white, and greater than 50 percent to black.

Pattern Dither uses standard fill patterns to define the one-bit image. Patterned images tend to look a bit tacky, but at times are useful.

Diffusion Dither takes the original image and attempts to simulate the different colors through randomly placed pixels. This is usually the best method of converting photographs into a one-bit image.

Custom Pattern simulates the effect of printing a grayscale image through a custom halftone screen. This method lets you apply a screen texture, such as a wood grain, to an image. You must first define a pattern in Photoshop to use this option.

To convert a color image to Bitmap mode, you must first convert it to grayscale. This removes the hue and saturation information from the pixels and leaves the brightness values.

Grayscale mode. Grayscale mode uses up to 256 shades of gray to represent an image. When Photoshop converts an image to grayscale, it only uses the brightness information of the original image. Every pixel of a grayscale image has a brightness value raging from 0 (black) to 255 (white).

Duotone mode. Duotone images consist of a grayscale image and one or more monochrome representations of the same image. Duotones, tritones and quadtones (all available under duotones) are commonly used make grayscale images appear to have a tint of color, such as sepia for the old-time photograph look. Each monochrome element of the image represents 256 shades of the particular tint color.

Indexed Color mode. Indexed Color images are based on an exact color table built from each color found in the image, usually up to 256 different color elements. Photoshop allows the development of a custom color table of any number of colors for a particular image. Indexed color images must be converted to either RGB or CMYK before they can be edited in Photoshop.

RGB mode. RGB Color images are 24-bit color images. RGB images consist of three channels - Red, Green and Blue - that define a color image. Most image editing operations can only be accomplished in RGB mode.

CMYK mode. CMYK Color images are usually known as four-color process images and are almost exclusively used in print publishing. Instead of the primary colors of light found in RGB images, process color images use Cyan, Magenta, Yellow and Black to define a color image. When combined in a four-color printing process, these colors combine to form the final color image.

Lab mode. Lab color consists of a luminance, or lightness component and two chromatic components, the a component, which ranges from green to red, and the b component, which ranges from blue to yellow. It is used most often when working with PhotoCD images or when you want to edit the luminance and the color values in an image independently.

Multichannel mode. A multichannel image is one that contains multiple channels, each having 256 levels of gray. They are used for specialized printing purposes, such as printing a grayscale image with spot color or converting a duotone for printing in Scitex CT format.

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