Profile Prism
Procedure for profiling a scanner

Topics of Interest

Using Profile Prism Software

Quick start instructions for profiling a scanner:

Note that scanning software varies greatly from one manufacturer to another. While the quick start instructions below describe the overall process of creating a scanner profile along with some recommended settings, we recommend reading and being familiar with the detailed instructions in the following section as well.

  1. Place IT8 target on scanner glass.
  2. Place piece of black construction paper on top.
  3. Close scanner lid.
  4. Open scanning software set software settings as recommended here.
  5. Scan the target and make sure target is not rotated in the scanned image.
  6. Bring image into Profile Prism and place four corner markers.
  7. Evaluate the messages to determine exposure, lighting, etc.
  8. Repeat 6-10 to correct any warnings.
  9. After placing four corner markers, set PP options as follows:
    • Type of device to profile: camera/scanner
    • Reference target: same as that shown on lower/right of ref. target
    • Profile description: scanner model and other info as desired
    • File name: click "..." and select a name for the ICC profile
    • Profile for: highest accuracy
    • White balance: allow profile to fix WB
    • Tone reprod. curves: do not normalize
    • Manual adjustments: all "normal" or zero
  10. Click "Create Profile"

Note: When scanning normal photos and using the profile developed above, it is important to scan photos using steps 1-5 above so that your photos are scanned under the same conditions as those used to create the profile.

The following describes the process for creating an ICC profile for a scanner using Profile Prism:

I. Acquiring the Image(s)

Before we use the software to create an ICC profile, we must do what we can to ensure that a quality image of the reference target is acquired. In this step, we must scan the IT8 reference target with the best settings possible. The reference target has 288 separate color patches that cover a wide range of colors. The object here is to acquire an image of this target with your scanner.

  1. Scanner preparation: clean the scanner glass with glass cleaner to ensure a quality scan. For best results, we recommend scanning with a black background. If your scanner has a white background on the underside of the scanner lid, cut a piece of black construction paper to the size of the scanner glass. You will use this paper in the next step.

  2. Target preparation: Place the reference target face down on the scanner glass and flush against the edge/top to ensure good alignment. Place the black piece of construction paper (cut in step 1) on top and close the lid.

  3. Scanning software: Open your scanning software and set scanning settings as recommended for your scanner.

  4. Scanning: To ensure that the scanner is fully warmed up, we recommend scanning the reference target twice and saving the second scan (discard the first scan). We have found that many scanners (especially Epson scanners) overexpose the first scan in a sequence if the scanner lamp was off prior to the scan sequence.

II. Using the Software


Step 1: Specify profile details

Before telling Profile Prism to generate your ICC profile, you need to specify a name, description and some options. Below is a description of each entry.

Step 2: Open and crop the image of the target

  1. Click "File", "Open Image" and browse to the folder that contains the image of the reference target. Select one of the images and it will appear in the image crop area in the upper right of the window.

  2. Next, locate the upper/left edge of the target in your image. To do this, use the horizontal/vertical scroll bars on the bottom or right of the image to scroll, or simply click on the image in the window and drag it left/right/up/down using the hand.

  3. Next, click the upper left crop corner button.

  4. Your mouse cursor will now change to an upper-left box corner when you move the cursor into the image area. Move this corner to the very edge of the target, placing it at the upper left edge of the black rectangle that surrounds the row/column labels as shown below. The corner marker is shown below as a black/white dashed line.

  5. Once positioned here, left click to place the corner mark. You will notice a red corner mark on the target image. If the corner mark is not exactly on the outside edge of the black corner as shown, simply repeat steps 3 and 4 until placed properly.

  6. Repeat steps 3 through 5, locating the other three corners of the target and placing their corner marks appropriately. Note that the top two corner markers should be placed at the edge of the outer/black rectangle surrounding the text row/column labels and the bottom two corner markers should be placed below the gray scale. Properly placed corner markers are shown below:

  7. Once all four corners of the target have been identified, the four "corner buttons" will only appear when you hover over them with the mouse. When all four corner buttons are "deactivated" and your target evaluation messages appear in the "Messages" area, you'll know that you have finished the cropping step. In addition, Profile Prism will overlay white "punchouts" on each color patch to verify alignment. The white punchouts should appear within each individual color patch on the target.

    Note regarding the "Jiggle corners" option: If the "Jiggle corners" option above the image is checked, Profile Prism will "jiggle" all four corner markers to try to obtain the most accurate target alignment. Note that this option may move the red corner markers so that they no longer align perfectly with the edges of the target. This is normal since obtaining the best overall/average alignment of the white punchouts may require moving some/all corner markers slightly. To place the corners manually without Profile Prism moving them, simply uncheck the "Jiggle corners" box and place the four corner markers again.

  8. Simply move around the target and make sure that proper alignment exists by ensuring that each individual color patch contains a white punchout and that none of the white punchouts appear to overlap into neighboring color patches.

  9. Finally, review your messages. At this point, Profile Prism has examined the image of the target and has evaluated white balance, exposure, and lighting of the target. The details of this evaluation are displayed in the "Messages" box on the lower portion of the window. Here is a list of messages that are displayed at this point:

NOTE: After you click "Create Profile" and the profile creation process has completed, the final messages displayed in the "Messages" box will be saved and associated with the image file that was used to create the profile. To recall the messages for a previous profiling session, simply click "File", "Recall Messages For" and select the image file used to create the profile. The messages will be recalled from the last time a profile was created based on that image.

Step 3: Generate the profile

Now it's time to sit back and let Profile Prism do its number crunching.

  1. Click the "Create Profile" button in the lower left corner.

  2. Note that Profile Prism will be performing billions of mathematical operations in the process of creating your profile, so it may take several minutes to generate a profile. You may follow progress by observing the progress bar at the bottom of the window.

  3. Note that once profile generation is complete, the location of your new profile is visible on the status bar at the bottom of the window.

  4. Make a final review of the messages displayed in the "Messages" box. Were any messages added? Profile Prism will add messages as the profile is being generated. These messages are:

III. Scanners and Metamerism

Metamerism is defined as a shift in color when viewing the same subject under different types of light sources. If you have ever matched clothing or fabric by examining against a swatch in a retail store only to find that what matched perfectly in the store is quite different under your home lighting, you have fallen victim to metamerism. Some types of lighting are good for evaluating colors while other light sources are inherently poor. Sunlight, for example, is a very good light source for evaluation of color due to direct sunlight having a smooth, full spectrum of color. Fluorescent and incandescent lights are examples of light sources that often bring out metamerism due to their poor coverage of the light spectrum.

All photographic media are prone to metamerism to some degree. To make matters worse, the cold cathode fluorescent tubes used as light sources in most scanners can bring out metamerism in prints since scanner light sources are neither full spectrum nor do they offer smooth coverage of the light spectrum. The photographic media used to create standard IT8 targets often shifts toward magenta under scanner illumination. The resulting profile will compensate for the magenta cast on the IT8 target by adding green. The profile will work perfectly for the scan of the IT8 target but since normal (film based) photographs will likely not contain the same magenta metamerism shift as the IT8 target, this often makes IT8 based scanner profiles appear too green when used on other media. Fortunately, there are ways to compensate for metamerism caused by the scanner light source and differing media.

Unfortunately there is no way to measure the effect of metamerism to compensate for it automatically. You may find yourself scanning a variety of media and the characteristics of that media with respect to metamerism will not be known. Fortunately, Profile Prism does offer two methods of dealing with metamerism when profiling a scanner. Simply put, if noticeable color shifts occur when using a scanner profile developed using the recommended settings at the top of this page, try changing "White Balance" from the recommended "Allow profile to fix WB" to "Device dictates WB" instead. When "White Balance" is set to "Device Dictates WB", Profile Prism will use the scanner's internal tone curves to compensate for metamerism in the IT8 target. This will result in a profile that works properly assuming no metamerism is present in the media you are scanning.

In addition, you may also use the matte CRxxxxxx target to profile your scanner (see camera profiling instructions for information on use of the matte target). The matte target is less affected by metamerism than the IT8 target and may provide more balanced results under your scanner's light.

IV. Utilizing Profiles Generated by Profile Prism

Note that the above instructions relate to generating an ICC profile for scanners. Since an ICC profile is a standardized method for describing how a scanner records color information, using these profiles with images from your scanner is a task left up to your imaging/editing software. Inexpensive software does exist which allows you to fully utilize ICC profiles for color management of images, batch conversion, etc. One such ICC aware application is Qimage, also produced by ddisoftware, Inc.. As stated elsewhere, consult the help or users manual of whatever ICC aware imaging/editing software you are using for assistance in making use of your ICC profiles once created. In Qimage, some relevant links that provide help and understanding of ICC profiles are:

Understanding ICC Profiles
Qimage Learn by Example: ICC Profiles Section

Note that whatever software you use, there is a standardized folder for which ICC profiles are normally stored. The following are "standard" locations for ICC profiles depending on the operating system used. It is recommended that you save your profiles in these locations since most software will look here for them:

Windows 95, 98, 98SE, ME: \windows\system\color
Windows NT/2000: \winNT\system32\spool\drivers\color
Windows XP: \windows\system32\spool\drivers\color