Site Development: Techniques

Scanning with the HP ScanJet 4p

Acquiring the Image

The HP ScanJet 4p installs itself as a TWAIN complient scanner and is available to any program that recognizes TWAIN devices. I am currently using Picture Publisher v.5.0a from Micrografx as my image editing/acquiring program.

After launching Picture Publisher (PP5), chose File|Acquire which launches the HP PictureScan software. The HP PictureScan software presents the Task Manager (Main Menu) with choices for different types of scaning tasks. Choose the appropriate task (the source material should be on the scanner bed) and choose Scan.

(Screen Shot (19K), HP PictureScan Task Manager)

Preview Scan

A preview image is scanned into the HP PictureScan preview window.

Simple image cropping can be performed at this point. If the image is badly aligned, you may want to Cancel this preview, adjust your source material on the scanner bed, and re-scan. This may be quicker than using your image editing program to rotate the image.

When you are satisfied with the preview scan, select Options where selections are made for Picture Type, Destination Device, Size Settings, and Preferences. Selections made for a previous scan are used until new selections are made.

(Screen Shot (24K), HP PictureScan Preview Window)

Selecting the Picture Type

HP PictureScan provides five picture types, each of which controls how many colors are captured from the source material.

Black and White Drawing (Yeilds: 1-bit color image (2 color))

Source material includes line art, clip art, mechanical drawings, pen and ink sketches, or anything with no intermediate shades of gray.

Black and White Photograph (Yeilds: 8-bit gray image (256 gray))

Source material includes black and white photos or drawing, anything with many shades of grey; also used for scanning color photos that are to be printed in black and white. Alternately, your image editing program may provide for resampling of a color image to grayscale values.

Color Drawing (Yeilds: 8-bit color image (256 color))

Source material includes a black and white drawing which also contains area of solid color, such as a pie or bar chart. In usuage I can see no difference between this selection and the next.

Color Photograph (Normal) (Yeilds: 8-bit color image (256 color))

The HP ScanJet manual suggests that this selection be used for images that will be presented on the computer monitor, but essentially you're capturing a 256 color image of the source material.

Color Photograph (Best) (Yeilds: 24-bit color image (16.8 million color))

Source material includes anything that is not line art. This yeilds the most color information in the image file, and although the resulting image file size can be rather large, it is eventually resized before being saved as a master image.

This is the selection that I scan all of my source material under.

(Screen Shot (25K), HP PictureScan Picture Adjustments)

Destination Options

HP PictureScan makes adjustments during the scanning process according to the destination you have set. Selecting the correct scan detination is important because HP PictureScan sets the best scanning resolution for that specific destination.

Here are the resolution yeilds for some of the destinations that I've experimented with:

300dpi HP LaserJet (resoluttion = 100)

600dpi HP LaserJet (resolution = 150)

This is the destination that I use. I realize that this is overkill for presenting images on the web, but this resolution seems to provide enough image information that the resulting downsampling/sizing of the image for screen presentation yeilds a good quality image.

Screen Presentation (resolution = 75)

(Screen Shot (24K), HP PictureScan Destination Options)

Size Settings

In most cases I scan at the original size. This can result in some very large initial files, but I want to have the most image information available before downsampling to the final master image file.

In cases where your source material is of a different size than the space available on the "page", it is best to allow the scanning software to size (specifically) the resulting image to the dimensions required.

(Screen Shot (24K), HP PictureScan Size Settings)

Image Editing with Picture Publisher v.5.0a

The following information is derived from my work on the Conan Project with all of the references based on having to scan book and magazine covers.

Original Scan

A typical magazine cover will produce an image 1213 x 1635 (W x H) (prox 8.5 x 11); as mentioned above I prefer 24-bit color at a resolution of (150). This initial image comes in at 5.8mb (average).

Any editing of the image takes place at this stage: rotating to square the image, retouching, and cropping. When I'm satisfied with the appearence of the image it is sized to a standard height (700) with the width value determined by the software.

After sizing I apply an Image|Effects|Sharpen filter which seems to "punch-up" or sharpen the detail (just as the name implies).

The image is then saved as a .pp5 file (essentially an uncompressed bitmap with propriatory information). This is what I refer to as a Master Image.

(Screen Shots (14K, 19K), PP5 Resize and Effects|Sharpen Dialog)

Master Image (??? x 700)

Typical Master Image: 516 x 700, 24-bit color, resolution = 150, 1.2mb

I settled on a standard height of (700 pixels) because it is almost twice as large as the largest image I would post to the website, and the resulting file size is a managable 1.2mb (average). I want to provide more than enough image information when resizing this image to a size suitable for posting on the web (and storing on the server).

After resizing the image is saved to a .jpg file. PP5 provides (3) compression settings:

High Quality/Low Compression (4:4:4)

Good Quality/Good Compression (4:4:2)

Low Quality/High Compression (4:1:1) (my default choice)

Although I can see a difference in image quality between the highest and lowest settings, the quality gained is not siginificant enough to warrant use of a file almost twice the size.

Web images are derived from this master image, and are essentially "throw aways". Because the .jpg format is lossy, it's never as good as the original and is of little use outside of the presentation framework of the website.

Cover Image (175 x ???)

Typical Cover Image: 175 x 237, 24-bit color, resolution = 150, 24k

The master image is resized to (175 x ???), the sharpen filter applied, and the image saved to a .jpg with the above mentioned compression setting. I've settled on this size because it lays out nicely on the webpage, and provides a large enough image without imparting too much download overhead.

Book Cover Image (135 x ???)

Typical Cover Image: 135 x 220, 24-bit color, resolution = 150, 12k

The master image is resized to (135 x ???), the sharpen filter applied, and the image saved to a .jpg with the above mentioned compression setting. I've settled on this size because it allows me to place two images within the width of the webpage.

Currently, I am using this size image for the Book Covers pages of the First Twelve Books section of the Conan Project.

Example

Poster Image (??? x 400)

Typical Poster Image: 295 x 400, 24-bit color, resolution = 150, 46k

The master image is resized to (??? x 400), the sharpen filter applied, and the image saved to a .jpg with the above mentioned compression setting. I've settled on this size because the height fits nicely in a full browser window with a monitor setting of 800 x 600, and it leaves enough empty screen width for text.