-> User's Manual -> Segmentation Settings

Segmentation Settings

Manual Edge Detection Segmentation : Older technology - See Auto-set Edge Detection Segmentation
Aggregate Pixel - On setting the size of the aggregate pixel
Color Sweeping - On setting the color sweep algorithm
Compatible Colors - On setting the compatible colors allowances
Extra Color Elimination - How to limit the number of colors
Orphan Pixel Elimination - On setting which orphan pixels to eliminate
Tier One - On setting the tier one transitions
Tier Two - On setting the tier two transitions
Transitional Blob Elimination - On setting the transitional blob elimination election
Eliminate Extra Colors - On setting the color elimination parameter
Eliminating Orphan Pixels - How to eliminate orphan pixels
Sweeping Colors - On improving color contrast

Auto-set Threshold Segmentation - Simple black and white segmentation

Manual Threshold Segmentation - Simple black and white segmentation

Auto-set Edge Detection Segmentation - Segment like a human

Manual Edge Detection Segmentation
Like actors in a play, images have a variety of moods. The Pac-n-Zoom® user will want to change the settings to produce the correct effect. For the most part, the settings allow the number of colors to be used. For example, the setting for an ever generous rose would allow for many more colors than the setting for hard and cold prose. There are three ways to set the settings. The first method is through the GUI (Graphical User Interface - the normal program interface) and the pull down menus. The second method uses macros through the CLI (Command Line Interface - such as a DOS prompt). The CLI allows the settings to be changed when running the in the batch mode. The third method is to edit the "Pac-n-Zoom.cfg" with a text editor. When Pac-n-Zoom is not running, the settings are stored in "Pac-n-Zoom.cfg" under the segment name of "VIDEO FILTER PARAMETERS". A typical segment of data might look like the following.

75 ; Tier one setting
75 ; Tier two setting
0 ; Aggegate pixel size
1 ; Color sweep setting
150 ; Orphan pixel merging color
1 ; Eliminate transitional blobs
75 ; Near color elimination
7 ; Number of colors allowed

These settings are typical settings for a 7 color (in other words 7 original and final colors - the number of scanned colors could be many thousand) document.

The following settings are listed in their order of importance. The settings at the top of the list are the most important.

Tier One
The first step in extracting information from visual data is to find the borders that have the highest contrast color transitions in the picture. In Pac-n-Zoom, these are known as tier one borders.

Tier one borders usually demarcate the primary artifacts of the picture.

The tier one setting should be set low enough to obtain all the critical information in an image. For example, when the tier one is set too high, parts of a letter may be missing.

When the tier one setting is set too low, the same letter can be set to several different shades or gradual changes can become a series of steps.

Use the following steps to set the tier one level.

1. Select Option: Set the display tier one border option.

2. Reduce Level: Reduce the tier one setting to where the image is segmented into too many blobs, and note the low setting (LS).

3. Increase Level: Increase the tier one setting until important demarcations are lost, and note the high setting (HS).

4. Calculate Level: Set the tier one level with the following calculation.

Tier 1 Level = (HS + LS) / 2

Click here to see some examples of correct and incorrect settings.

The input device usually causes image degradation along high contrast borders. Pac-n-Zoom restores the tier one borders to closer approximation of the original image.

Aggregate Pixel
Nearly every computer image, except the few painted ones, was captured by wave front optics focusing an image onto charge coupled semiconductors.

Any number of distortions (some of them are mentioned above) append themselves to the image. In particular, a high contrast color transition will tend to scatter hundreds of orphans.

The optics blur the image. The depth of focus problems are particularly destructive, but color level flutter and optical chromatic aberrations add their fair share of damage.

Besides optical and transition distortions there are a range of frequency and spatial problems that include Nyquist noises and Johnson aliases.

These are three areas where the image is compromised but there are at least several more.

A single pixel on these captured images won't mean much, unless it constellates with its nearest neighbors. The aggregate pixel setting is an abstract setting that partially determines the number of pixels needed to make an artifact significant.

Pac-n-Zoom uses aggregate pixel setting in several places, and several problems can occur if it is not set correctly. There are, however, only two aggregate pixel settings (0 and 2).

0: This setting should be used on all pictures except video. Its size is 2 by 2 pixels.

2: Should be used on video pictures. Its size is 4 pixels wide by 2 pixels high.

Tier Two
A gradual change in color will not trigger a tier one artifact, but over a number of pixels, the color can change significantly. To insure the fidelity of the image, the color should not be allowed to change within the range of human recognition without starting a new blob. The tier two borders serve this purpose.

Most humans can see the difference between 4,096 and 32,768 colors, but only about 18% of the people we tested could see the difference between 32,768 and 262,144 (6 bits for each primary color when using 3 primary colors) colors.

The tier two setting does not set the amount of the actual jump (change in color) between adjacent blobs. It sets the amount the original picture is allowed to change inside what will become one blob (remember: a blob is all exactly the same color; the change inside the blob refers to the amount of change allowed in the underlying pixel that will be grouped into the exact color of the blob). For example, a tier 2 setting of 9 means that the extreme individual pixel colors inside a blob are within 9 color levels of each other. Therefore, tier 2 blobs insure the fidelity of the image.

When two adjacent blobs have a visible color jump, a contour line forms ( click here to see some examples of contour lines).

When tier two settings are set too high, the contour lines will stand out more than desired.

The following steps can be used to set the tier two settings.

1. Tier One: The tier two blobs are layed inside the tier one blobs. Therefore, the tier one setting must be set first.

2. Select Options: Set the display tier one and display tier two options.

3. Set High: Increase the tier two setting until the contour lines are too visible.

4. Decrease Level: Decrease the tier two setting by about 30% (this is an arbitrary amount). For example, if the high setting (from step 3) was 16, the nominal setting would be 11.

Compatible Colors
The tier two sets the amount of fidelity to the original color. It does not specificallly set the amount of jump between two terraces.

For example, suppose the color level on adjacent pixels were ramping as shown in the chart. If a tier two blob started at pixel number one and if the tier two blob setting was 9, a new blob would start at pixel 4 (because the 69 on pixel 2 has to be in a different tier 2 than the 79 on pixel 4).

Pixel Number 1 2 3 4 5 6
Color Level 76 69 77 79 72 74
Average Color 74 75

Therefore the color is terraced to jump one pixel. If the compatible color setting was set to 1 or larger, the two blobs in the table above would be merged together. They will also be merged with other colors throughout the image that are within the tolerance set by the setting.

Fewer colors will compress further, but when taken too far, the image will begin to look coarse (like a cartoon instead of a photograph).

From our experience, the following are appropriate compatible color settings in color levels.

1. Photographs - 9
2. Video - 15
3. Line Art - 150

Eliminate Transitional Blobs
In the perfect world, if the aggregate pixel setting is set accurately, the color should not be changing for more than the aggregate pixel length. This theoretical ideal is often violated from various fluctuating distortions (in other words, the distortion in different parts of the picture are different) such as depth of field issues. For example, the depth of field can be dramatically different between the background and foreground of an image. Therefore, in the real world, the color transitions (the amount of space it take the color to change from one level to the next) can exceed the aggregate pixel length.

Whenever transitional colors extend beyond the aggregate pixel length, entire blobs can be transitional.

Even when the documents are scanned in, it may be desirable to eliminate transitional blobs. For example, if there are almost any color bleedings from the printing process, they will result in transitional blobs.

A transitional blob is defined as one where the maximum height or width is either the aggregate pixel size or smaller, and all colors transition in reference to the tier two setting. When we say "references the tier two setting," we mean the color changes more than the tier two settings. The three possibilities are plateaus, ramps, and extremities ( click here to see them).

Plateaus and ramps are considered transitional blobs, but if any color is an extremity, the blob is not considered transitional. This logic removes the transitions that lie between major blobs without deleting small amounts of data that doesn't transition.

The removal of transitional blobs takes some of the softness out of a picture. The transitions will tend to be more abrupt (higher contrast). Greater contrast is usually appreciated in text documents and line art but depreciated in photographs and video.

When transitional blobs are removed, spacial ( geometric and statistical) compressors will have higher compression ratios.

The eliminate transitional blob setting has two valid values.

0: The transitional blobs will not be eliminated.
1: The transitional blobs will be eliminated.

Eliminate Extra Colors
The Pac-n-Zoom segmenter allows the user to specify the maximum number of colors in the picture. The colors with the highest pixel count are left in the picture. A first with the most system is used to break ties (the first colors found, starting from the upper left hand corner then going right before down, are taken over later colors).

The elimination of extra colors deletes color and geometric detail from a picture. Since the image restoration is not perfect, most of this detail is from sensing distortions.

Users with photographs will probably want to set this setting at about 80,000 for the Internet, and at 250,000 for professional photography. As of this writing, we are not entirely certain of the effects, and settings greater than 250,000 might be desired in some cases.

Video users will probably want to set the setting at about 70,000 (this is a guess). For streaming video, values of 12,000 might be in order (another guess).

In document handling and line art, the number of colors is often minimal (usually between 2 and 5). Therefore the setting is obviously set to the number of shades in the picture.

When extra colors are removed, spacial (geometric and statistical) compressors will have higher compression ratios.

Eliminating Orphan Pixels
This setting determines the amount of contrast necessary to leave an orphan pixel in the image. On the extraction side, it could be argued that orphans are worthless and should always be eliminated regardless of the amount of contrast. To implement this opinion, the setting should be set at 255.

For the most part, orphans don't help photographs or video and hurt line art and text documents. Orphans will lower the compression ratios of all compressors with the possible exception of transform compressors Furthermore, orphans will prevent raster to vector conversion in Pac-n-Zoom's data-tagger. Therefore, orphans should usually be eliminated.

The orphan pixel setting has the following meaning.

0: All ophans will be accepted.

140: Orphans that have a color contrast of more than 140 on any primary color will be accepted. The number, "140," can be any number between or including 0 to 255.

255: No orphans will be allowed.

Sweeping Colors
This setting selects the image restoration algorithm. We have tried a couple of setting, and we like the current one best.

Different distortions types should theoretically use different algorithms.

The current setting needs to be set to one.

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