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Scanning Images

Scanner Resolution, Image Type Recommendations
Purpose of the scanned image	Image goals	Best image format to use	Resolution to use	Color mode to use
Copy an image with color gradients (like a photo) to place on a web page or email to someone	Small image file size (quick to download) Common format that doesn't require image editing software	JPG, progressive scan	70 to 100dpi	True color, 256 color
Copy an image with poster-like color (like an icon) to place on a web page or email to someone	Small image file size (quick to download) Common format that doesn't require image editing software	GIF	70 to 100dpi	True color, 256 color
Copy a photo or an image to be preserved, edited, or enlarged and printed	Best image with most resolution and most color to allow more options when editing the image later and more options as computer capabilities increase	TIF, uncompressed	highest hardware (optical) resolution of scanner - 300dpi minimum	True color
Print	Best image the printer can print (be aware of ink and paper longevity)	N/A if print directly from the scanner	Same resolution as printer to print same size as original; higher resolution if you will be enlarging the print. ** See Note below	True color
OCR	An image the OCR software can interpret with the fewest mistakes	TIF	150 - 300 dpi	Grayscale

** Some people recommend scanning at about 1/5 to 1/3 of the printer resolution.

Also be sure to use your printer options: select photo paper if you are using that, select "best" printing mode. These options are usually found by clicking on Properties, Setup, Advanced or some similarly worded button on the print pop-up window.

Scanning and Digital Images Basics

Some of this info is personal opinion, some is gathered from recommendations seen on mail-lists and web sites, some from scanner manuals and other books.

No one can tell you exactly what options will work best for your scanner and printer and your photo editing software - you will have to experiment. But the recommendations below can give you a starting point that has given good results for many users. The chart is shown first so it is easily found on the first pages of the handout. The rest of this document explains how scanners work, defines these file types and other terms and will help you understand why the values in this table are recommended and what other image formats, resolutions, and color modes might be best suited for your particular needs.

A lot of the information details here are simplified for easier understanding. But once you understand the basics you can then understand the more in-depth details from a manual on scanners or computer images.

Basic Steps In Scanning A Document and Saving It As a File
1. Place image on scanner bed
2. Click scan button to get preview image
3. Select the area to be scanned and saved
4. Select the resolution
5. Select the color mode (color depth)
6. Select save to file and enter a file name (or select print if you want to print it on the printer)

Additional Tips:
• More computer memory will make image editing easier and less frustrating
• Always backup your images to media other than your hard disk so you don't lose them if the computer crashes: use a ZIP drive, CD-R/CD-RW, tapes, etc.
• Always scan an image at 300 to 600 dpi and in true color (even if the photo is black and white) for preservation then it can be manipulated in photo editing software to make the file size smaller - but you'll hjave themaximum amount of data to manipulate. An exception to this would be if you know you are never going to do anything with this image other than place it on a web site or email it to someone who won't need the additional resolution.
• Always work on a COPY of your image - NEVER work on the original scanned image.
• Don't use the proprietary image format that many editing packages want to use as the default - PDD for PhotoDeluxe, PSD for PhotoShop, PSP for Paint Shop Pro, etc.

Where To Find more Info Online

A Few Scanning Tips - http://www.scantips.com/

Screen Genes (Digital Image Manipulation Tips) - http://www.screengenes.com/

Ancestry.com Online Articles by George Morgan and Others - http://www.ancestry.com/

and hundreds of other sites you can find by using a search engine such as google.com.

Help in dating old photos - http://www.siue.edu/COSTUMES/history.html

Definitions of Terms

• Color mode / color depth / color palette
  • = the number of bits of color information for each pixel or dot
  • - 1-bit color image can only display 2 colors: black and white
  • - 8-bit color image can display up to 256 colors (also used for grayscale)
  • - 16-bit color image can display up to 65,536 colors
  • - 24-bit color image (True color) can display up to 16.7 million colors (256 values each of red, blue, and green)
• DPI = dots per inch - the more dots per inch the sharper an image will appear
• OCR = Optical Character Recognition - the process of taking a scanned image (a picture) of text and converting it from an image to a text file
• Pixel = Picture element - a dot (for our purposes)
• Resolution
  The resolution of a scanner is measured in dots per inch, usually abbreviated as dpi, and is based on the number of photo-sensitive cells contained in the scanner. The scanner may be able to create a lower or higher resolution image using software to manipulate the number of dots (interpolation) so you usually see scanner resolution listed as something like 300x1200 dpi. This means the scanner has a 300 dpi hardware (or optical or physical) resolution that can be enhanced to 1200 dpi using software or interpolation. The important number when purchasing a scanner is the lower number - the maximum hardware/optical resolution. For photo preservation you will want a scanner with a minimum of 300 dpi resolution and 600-1200 dpi would be better.
• Thumbnail - a small representation (quickly downloaded) of a larger image - used for preview images and often on web pages where you then click to see the full-scale image
• Vector vs. Bitmap image
  • A bitmapped image has a "bit" (or several bits) to "map" each dot of the image - arranged in rows and columns.
  • A vector image contains a set of instructions to draw objects (shapes, lines, text). For example, start at some x,y coordinate and draw a line of color red that is 100 pixels in length and ends at some other x,y coordinate.
• Two basic types of files are stored on a computer - human-readable text and non-text or "binary" files.
  • Text files often end with the suffix .txt and if you open them with a word processor or text editor you will see alpha-numeric characters you recognize: a, b, c, D, E, F, 1, 2, 3, ., #, etc. Even though these characters or "bytes" are actually stored in a code the software on the computer knows to display them as human readable characters.
  • Non-text files come in MANY forms:
    • .exe - executable file (a program)
    • .rtf - Rich Text File
    • .ged - GEDCOM file
    • .psp - Paint Shop Pro image file
    • .pdd - PhotoDeluxe image file
    • .psd - PhotoShop Image File
    • and 100's more

Common Image File Formats File format is important for image preservation and because some programs cannot display some image types. To share an image file with a friend you would want to be sure and use a format they can display. Almost all image editing programs can display and save files as any of the formats below. Many programs also have their own proprietary image format and they default to that format. So you have to search for the "Save As" or "Export As" options to use the common formats. If you save your files in the programs proprietary format and you switch to a new program you will probably have to convert all of your images to a common format the new program can read. If you start out saving all your files in the common format then you should be able to change programs as often as you like and still use the images.
SUFFIX	FULL NAME	COLOR MODE	COMPRESSION	ADVANTAGES / DISADVANTAGES
GIF	Graphic Interchange Format	8-bit color	loss-less	- any graphical web browser can display on all platforms - NOT good for photographs - best for logos, icons, line art, images with flat areas of color
JPG	Joint Photographic Experts Group	24 bit color; grayscale	lossy ## See Note below	- any graphical web browser can display on all platforms - best for true color images and grayscale images
PNG	Portable Network Graphics	24-bit color	loss-less	- has not been widely adapted across all platforms - requires newer browsers to display this format - file sizes are larger than a JPG would be
TIF/TIFF	Tagged Image File Format	24-bit color; grayscale	loss-less	- NOT usually displayable by web browsers; requires image editing software - best (most commonly supported) format for photo preservation, enlargements and editing - supported by all standard image editing programs (JASC Paint Shop Pro, Adobe PhotoShop/PhotoDeluxe/Elements, MS PictureIt, Ulead IPhoto, etc.)
BMP	Windows Bitmap	24-bit color; grayscale	loss-less	- images are MUCH larger than they would be in a JPG or GIF format

## NOTE: JPG is a "lossy" compression scheme - you lose some data each time you re-save the image as it gets more compressed - ALWAYS save the original and do your editing on a COPY of the original file. However JPG: - can reduce a file size by up to 96% by removing some color information - usually have a choice as to how much compression should be used when you save an image as JPG

Basics of How a Scanner Works

When you scan a document the light bar moves down the carriage under the glass. The light is reflected off the document, through mirrors, and depending on the exact technology of the scanner itself, through filters and/or lenses to an array of photo-sensitive cells. Electrical signals are produced by these cells that indicate the intensity and color of the reflected light. The signals are interpreted and saved in the computer then displayed on the screen, printed or saved in a file.

As the light source moves down the carriage it reflects the light and makes a bit-mapped image of the document. This means each dot or point of the image represents a point on the document - not a character or word. So even when you are scanning a document that is words or text you are making a "picture" of the document - not a text copy of the document as you make when you type the letters using your keyboard and a word processor program. The printed copy of a scanned image may LOOK the same as the original document but it has a completely different representation inside the computer.

Images or pictures take a lot more disk space to represent than does the text document you type into a word processor.


To represent the word "HI" in a word processor it only takes 2 characters of space in a file - the code for an "H" and the code for an "I".

To represent the scanned image of "HI" the amount of space in the disk file will vary depending on the resolution (or dpi) used for the scan and whether you save in black-white, grayscale or true color mode. Another factor that will affect the file size is the type of compression used in the image format. That number is not reflected in the charts below.

For the image shown above which is 15 dots wide x 11 dots tall would need the following amount of space in a disk file. For the example lets say this image was scanned at 75dpi. The exact numbers are not really important - what you should remember is:

• the more dots per inch (resolution) the more bytes in the saved file
• the more colors per dot (color mode) the more bytes in the saved file

Questions To Ask Yourself To Allow Using Your Scanner and Digital Image Software Effectively
• 1. What Will You Be Scanning?
  • photos
  • 35mm slides, film negatives (requires special scanners/features)
  • documents such as NARA pension files (do you need an 8.5x14" scanner or will you be happy with scanning pages in 2 parts?)
  • books at a library (does the scanner require a power outlet and how heavy/bulky is it?)
• 2. What Do You Plan To Do With The Image After Scanning It?
  • email it to someone
  • view it on your computer screen
  • put it on a website
  • enlarge it and print a copy
  • make a book that will be photocopied or put something in a newspaper
  • use photo editing software to fix scratches, etc.
  • save the image to pass it down to future generations
  • use Optical Character Recognition (OCR) software to convert scanned images to text
• 3. What is the hardware/optical resolution and the modes or color depth of your scanner?
• 4. What is the resolution of your printer if you plan to print the images? Also, does your printer allow for more resolution through a software feature such as HP's PhotoRet?
• Answers to these questions will affect the
  • resolution (dots or pixels per inch)
  • scan type or color mode
  • file type you will save the image as (JPG, TIF, GIF, PNG, BMP, etc.)
  • other software you may need
  • what kind of scanner you need

If you use Paper Port: http://support.visioneer.com/customer/
Click on "Tech Tips" in the left hand navigation bar.
Click on "Using Paperport" in the table on the page.
Click on "Attaching pictures to email" and it has some instructions about saving a file as jpeg.
Open PaperPort
Open a photo
Click File
- Export
- get a popup window, look at the bottom left
- select "Export Files of Type" - change to JPG

How to Attach Files to email:
1. Choose New Mail/New Msg from the menu.

2. In the New Message/Compose window, enter the appropriate information in the "To," "Subject" and "Message" areas.

NOTE: With all of the worry about viruses in attachments you should always send an email first telling the user you are sending a second email with an attachment and what that attachment will be. Also, when you email the attachment place some explanatory text in the message box. Many people will ignore email that comes with no message and only an attachment as this is common with viruses also.

3. Click the Attach File button on the upper toolbar.

4. Browse through the drives and directory folders until the desired file is found. Highlight the file and click Open.

5. The attached file appears as an icon in the message area or the name shows up in the Attachments area. Click the Send button to send the e-mail.

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