Advancing Knowledge through Technology

Printing and Scanning Software

Printing

The main lab is equipped with one printer to which all jobs are sent.

Cancelling Queues/Rebooting the Print Server

Clearing Paper Jams / Refilling printer

If the printer displays the prompt 'paper jam' follow these instructions:

  1. Contact a CHASS Staff member.
  2. If the printer display indicates Tray Empty please notify a CHASS Staff member.
  3. Do not attempt to reset the printer or clear any paper jams yourself

Scanning


Basic Definitions and Concepts

A number of variables have to be taken into consideration when scanning images for printing or for the Web.
DPI
Dots Per Inch. A measure of the output resolution produced by laser printers or imagesetters. See also LPI.
LPI
Lines Per Inch. A measure of the frequency of a halftone screen used in printing. The archaic, and now misleading term line harkens back to the diffraction line etchings used to create analog halftones
SPI
Samples Per Inch. Used here to indicate the number of data points per inch that a scanner captures (i.e. input). As opposed to DPI (dots per inch), PPI (pixels per inch), or LPI (lines per inch) - all of which refer to output.

Resolution

Most scanners have two different resolutions: the optical resolution (the actual number of pixels a scanner can acquire) and the interpolated or enhanced resolution (a means of mathematically enhancing the resolution).

Things to keep in mind:

Optimum Resolution Settings

The optimum resolution for a scan primarily depends on the type of artwork being scanned (line art, grayscale, colour), and the final output of the artwork.

Line art

Line art (black and white illustrations, text, logos, etc.) should be scanned at the highest possible resolution and then resampled to match the final output. For instance, printing line art at 1200 dpi to a 600 dpi printer will not produce a better image.

Grayscale

Grayscale images should never be scanned beyond the optical resolution of the scanner. The actual resolution depends on the halftone frequency of the final output device. A formula to keep in mind is
resolution = halftone frequency x 2

You may even want to try scanning at less [halftone frequency x 1.25, 1.5, or 1.75) to minimize the size of the file. For instance, a 300 dpi laser printer has a maximum halftone frequency of 60 lines per inch, which means that the scanning resolution needs to be no more than 120 dpi (60 x 2 = 120). Sending a higher resolution image to the same printer will not increase the quality of the output.

The halftone frequency of the HP LaserJet 5mp Printer at the CHASS Electronic Publishing Centre is ca. 75 lpi. Thus, if you are scanning grayscale or colour images for final output on this printer, you should scan your images at no more than 150 dpi.

Colour Images

Scanning colour images follows the same guidelines as scanning grayscale images (i.e., resolution = halftone frequency x 2).
Note: Scanning for final output with imagesetters or film separations requires high-end scanners. If you are scanning for final output to a colour laser printer you will need to find out whether the printer is a halftone or continuous tone printer (a continuous tone printer produces an image without dots and with almost photographic quality). If the latter, then you can often scan your images at less than the final output. For example, for output to a 400 dpi continuous tone colour laser printer you could scan your images at 150-200 dpi and get great quality (though you will get better quality if you scan at the same dpi as the final output).

Scanning for the Web

The same basic principles noted above apply when scanning images for the Web. The optimum resolution is dependent on the resolution of the final output, which in the case of the Web is monitor resolution: 72 dpi (or more technically 72 ppi - pixels per inch).

The only time you may want to scan at a higher resolution is when you are scanning line art. In this case you may want to over scan the image, i.e., scan at a higher resolution and then resample the image to a lower resolution in an imaging program like Photoshop. This may yield a higher quality image.

Another consideration when scanning for the Web is the bit depth of the scan. If the final output for the scan will be a GIF (Graphic Interchange Format), which has a maximum bit depth of 8, you may want to scan with that bit depth (= max 256 colours). Note that you can also reduce the bit-depth in an imaging program like Photoshop (you will probably want to further reduce the bit depth to lower the file sime of the GIF image).

If you are scanning photo-realistic JPEG images ten you will want to make sure that you are scanning at 24 bit (millions of colours) or higher.

Scanning with DeskScan II Software

ScanJet is the scanning software available with the HP ScanJet IIc in the Scanning Room at the Electronic Publishing Centre (14th floor Robarts).

Use the following table as a guideline to scanning at CHASS:

Type of Artwork Final Output DeskScan Settings
Type Path
Line Art GIF Web page B&W Drawing Screen (image at 75 dpi)
Grayscale JPEG Web Page B&W Photo Screen (image at 75 dpi)
Colour graphic - GIF Web page Color Drawing/ Color Photo (8 bit) Screen (image at 75 dpi)
Colour photo - JPEG Web page Millions of Colors (24 bit) Screen (image at 75 dpi)
Line Art LaserJet 600 dpi laser printer B&W Drawing LaserJet 5 (image at 150 dpi)
Grayscale image LaserJet 600 dpi laser printer B&W Photo (256 grays) LaserJet 5 (image at 150 dpi)
Colour image ScanJet 600 dpi laser printer Millions of Colors (24 bit) LaserJet 5 (image at 150 dpi)
Line Art Colour CT laser printer B&W Drawing Color LaserJet (image at 300 dpi)
Grayscale image Colour CT laser printer B&W Photo (256 grays) Color LaserJet (image at 150 dpi)
Colour image Colour CT laser printer Millions of Colors (24 bit) Color LaserJet (image at 150 dpi)

More Scanning Tips

The following document offers some basic tips on scanning at the CHASS publishing centre. Please be aware that you are responsible for knowing if the material you scan is copyrighted or not. OmniPage and Photoshop manuals are available from Claire.

Scanning text

Recommendation: Use clear photocopies rather than a bound book.

Place document on flatbed, face down, or, use about a quarter inch of paper at a time, face up, in the feed on the top of the scanner (software prompts you to add more paper). If using the feed, put the green lock handle in an upright position, place paper in the feed face up, then click the green lock handle down to secure the pages.

Open OmniPage Pro

From the Properties menu, click on Use Defaults. This clears settings from the last user. Go back to the Properties menu and change any settings you need (i.e., languages, double sided paper, etc.).

Click Auto

The document will be automatically scanned. When the document is scanned, a prompt begins OCR (optical character recognition). This is where the software stops on each word it could not understand (words it cannot understand will be highlighted in red, green, or blue). You are prompted to edit the text as you go. If this is too time consuming, simply click on Done, and the prompt asks you to save the document. You can then edit the document in a wordprocessor instead.

To save the document, it is recommended you save it in both OmniPage's own format (.met), as well as your own wordprocessing format of choice (e.g., Word, or WordPerfect). If you save the document in .met format as well, you will have the option to open the file again in OmniPage at a later date in case you would like to run OCR on it again without re-scanning. SAVE THE DOCUMENT TO THE HARD DRIVE FIRST, NOT DIRECTLY TO A DISKETTE. Once the document is on the hard drive, you can copy it to a diskette (use Windows Explorer). Then please remember to delete your file(s) from the hard drive.

Scanning images (to be used in a word processed document)

Place photograph or image face down on the flatbed

Open DeskScan

Under Type, select the type of image (e.g., sharp millions of colours is recommended for a colour photograph or image with numerous colours) Under Path, select LaserPrinter 5 (this allows the final output format to be printed)

Select Preview and the document will be automatically scanned. It is recommended that once the preview is completed, you drag the cropping box around the image so that only the image portion of the page is selected.

Select Final when you are ready to save the document. The scanner re-scans at this point, then a dialogue box will pop up for you to save the document. The default file type is a .tif format.

A .tif file may be opened in any graphic-based word processor such as Word for Windows (or Mac) or WordPerfect for Windows (or Mac). In your wordprocessor, there should be a menu item such as Insert. Select Insert picture from file. Your picture will be dropped into the wordprocessor.

Scanning images (to be used on the Web)

Recommendation: Visit the CHASS tutorials web site at:

http://www.chass.utoronto.ca/chass/tutorials/

and select:

there is a wealth of information about file types and more at this site. Included are hands-on exercises for using PaintShop Pro to create and manipulate images.

First, follow the procedure as for scanning images for wordprocessed documents as above, but this time, select the Path as Screen (not Laser Printer 5). This allows the output to be for a monitor, rather than for print out.

After you edit the image (see below), you will need to convert the .tif file to either .gif or .jpg for it to be loaded on the Web. Basically, a .gif file contains a maximum of 256 colours. Usually, cartoon-like pictures are saved in this format. A .jpg file is used primarily for photographs, and can contain 16.7 million colours. Converting to the different formats will be outlined below.

Editing File Size

Before you convert an image file, it is usually essential to edit the image file, both in terms of file compression size, and actual "pixel" size. A pixel is a unit of colour on the screen. 72 pixels equals 1 inch. Generally speaking, an image for the Web should be no larger than 500-600 pixels wide (due to most screens still being about 14"). You can change the image pixel size by opening the image in either PaintShop Pro or PhotoShop. Using PhotoShop, select Image, Image Size. Leave Constrain Proportions selected. Simply change one of the dimension sizes and the other will be automatically re-sized in proportion. Note: due to the fact Photoshop is a bitmap image editor, it is difficult to enlarge a picture without it being distorted. It is however, easy to decrease a size.

Editing Compression Levels

Now that you have changed the dimension size of your image file, you may like to further edit the file using PaintShop or PhotoShop's many filters, and tools. This document does not cover tool usage, but there are numerous online resources, and CHASS has manuals if you ask. To get you started however, in Photoshop, be sure to change the Image Mode (under the menu Image) to RGB format. This allows you to edit the image and use all the tools. Once you have completed the editing, if you are saving the file as a .gif format, you will need to select Image Mode, Indexed. This will "flatten" the file, and compress it to a maximum of 256 colours. Be sure to select "Interlaced", rather than "Normal" when prompted. An interlaced .gif will load on the Web with pixels filling in all at once, rather than suddenly showing up after a minute.

If you are saving the image file as a .jpg, DO NOT INDEX it. You want to keep the millions of colours, so select under Layers, Flatten Layers. This flattens the layers, without reducing the number of colours. Now when you select File, Save As, select .JPG as the format. You will be prompted with a dialogue box that asks you the compression level. Generally, I select 5 or 6, and check for any image degradation. Also, be sure to select "Progressive encoding" which will have the same effect as an interlaced .gif (above). Only Netscape supports progressive encoding. Be sure to check your image size in kilobytes. If it is too big, go back to your original .tif, and adjust it in terms of pixel size and compression. Then save again as a .jpg. Generally, it is best to always edit a .tif file, rather than a .jpg. If you keep opening and editing a .jpg file, it will degrade each time.

Extra Hint

Be sure to always include your image dimensions in your HTML coding. This helps with download speed. A properly coded image file looks something like this:

<IMG SRC="filename.gif" WIDTH="200" HEIGHT="40" ALT="short description" BORDER="0">

The ALT statement should be a short text description of the image, for those who use text-based browsers. The BORDER="0" allows for no link coloured border to show up if you decided to make the image a hypertext link.