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Image Enhancement

You may want to do enhancement with your scanned image. Color 2000 provides some effecial functions for you to modify scanned image, such as setting highlight and shadow for your image, adjusting the image curve, neutralizing your image, inverting your image, change the color balance for your image and so on. Image Enhancement consists of several functions. These functions have been placed together in a tabbed dialog box. To access one of these functions, just click on the protruding tab at the top of the dialog to bring it to the front. At the top of each dialog box there are thumbnail representations of the original and enhanced images ("Sample 1& 2"). You can see the effects of changes to a previewed image through the "Sample" thumbnails without committing yourself to full image processing. Original is the thumbnail view for the previewed image and "Sample 1 & 2" are the thumbnail views for the images after they have been enhanced. "Sample 1 & 2" give you a means of comparing two enhanced images. Click on the desired Sample to choose the required image and click the "OK" button to finalize the selection. Each function is expained below. Simply choose the one that you want to know and click your mouse. The corresponding information will be displayed and show you what effect of the image you will get. | Click the topic that you want to get into. Level Adjustment Curve Adjustment Neutralize Color Adjustment Color Balance Invert

Level Adjustment

The Level Adjustment dialog box shows the distribution of brightness levels in your image. To adjust the histogram plot, drag the triangular handles, located below the horizontal bar, to desired values. The left (black) handle controls changes to the shadow levels. The right (white) handle controls changes to the highlight levels. The middle (gray) handle controls changes to the midtone levels.

By varying the Shadow points and Highlight points you can change the relative shades and highlights of the image. The Shadow point represents the darkest value and the Highlight point is the brightest value. The Midtone point represents the gamma setting for your particular screen. On the histogram, the Shadow and Highlight scales are divided into 255 units.

Therefore, all pixels in the original that are darker than the current shadow point are now completely black in the enhanced image. Conversely, all pixels in the original that are brighter than the current highlight point are now completely white in the processed image.

Setting the highlight point to 200 renders all pixels greater than or equal to 200, on the original, completely white in the processed image. Similarly setting the Shadow point to 200 renders all points less than or equal to 200, on the original, completely black in the enhanced image.

The Midtone is a relative measure of the gamma of your monitor. The scale for Midtone ranges from 0 to 255. The gamma curve is on a geometric series. That means at a value of 255 it tends to infinity. The Midtone is bound by the Shadow and Highlight terms and cannot exceed them at any time. So, a gamma of 1 is equivalent to a Midtone of 128 providing the Shadow is set to 0 and the Highlight is set to 255. Similarly, if the Shadow is set at 20 (lower bound) and the Highlight is set at 220 (upper bound), a gamma of 1 is equivalent to a Midtone of 120.

You can restrict the effect of the Histogram plot changes to a single color by selecting either the Red (R), Green (G), or Blue (B) channel buttons. Or you may select the Master channel to apply the Histogram to all three channels.

Note: If you are using a Grayscale image type, the RGB readings do not appear in the dialog box.

Operation:

1. Open the Enhancement dialog box and select the Level Adjustment tab.
2. Choose the channel to be modified.
* Select Master to change all (Red, Green, Blue ) colors in the histogram simultaneously.
* Or, select one of Red, Green, or Blue to change the histogram representing that color.
* Or, select grayscale for grayscale scanners only.
3. On the histogram, use the mouse key to click on the Black, Gray or White triangular indicators to make changes to the Highlight, Midtone and Shadow respectively.
4. To see the changes and compare them to the original previewed image, click on the "Sample 1" thumbnail to see the enhanced image.
5. To make a second enhancement for further comparison, click on the "Sample 2" thumbnail to see new enhancements to the original and thus see a comparison between the thumbnails of "Sample 1" and "Sample 2".

Original | Sample 1 | Sample 2

Click "OK" to accept the changes and leave the Enhancement dialog box. Click on the "Cancel" button to abandon any changes and leave the dialog box. Click the "Auto" button to allow the software to make appropriate highlight and shadow adjustments.
Curve Adjustment

Select the Tonal Map tab from the Enhancement tabbed dialog box

The Tonal Map is yet another way to adjust highlight, midtone, or shadow levels in your images. When you open the Tonal Map dialog box, a tonal map consisting of a diagonally straight line appears. Notice that at every point on the default tonal map, the output shadow, midtone, and highlight brightness levels are equal to the input shadow, midtone, and highlight brightness levels.

The shape and slant of the tonal map represent brightness level ratios between the input of the original image and the output image data. By clicking on the tonal map line, a "hand"-shaped cursor will appear which can be dragged in such a way as to alter the shape of the tonal map line. The horizontal axis represents the original input brightness and the vertical axis represents the enhanced brightness. Values on either scale range from 0 to 255.

If you deform the curve into a convex shape above the original diagonal, the enhanced image will be brighter than the original.

| Normal Image | Lighten Image

Conversely, if you deform the curve into a concave shape below the original diagonal, the enhanced image will be darker than the original.

| Normal Image | Darken Image

In addition, if you want to invert the image colors such that their color complements become dominant, change the incline of the diagonal from a positive slope to a negative slope. Therefore, a diagonal will be drawn from the top left to the bottom right.

| Normal Image | Inverted Image

Operation:

1. Click on the Tonal Map tab to display the Enhancement dialog box for tonal mapping.
2. Click on the Tonal Map curve, a handle appears which can then be dragged to alter the shape of the curve as described above.
3. Click Save to save the changes as a customized setting. A Save As dialog box will appear upon selection of this button. Enter the name for the customized curve and click on the "OK" button.
4. Or, select the "Load" button to load a previously saved Tonal Map. An Open dialog box appears for you open the desired files.
5. Or, click on the "Reset" button to return the Tonal Map to the default diagonal as in the original.
6. Select the Histogram button to see a histogram of the changes made.
7. Select the "OK" button to accept all the changes or the "Cancel" button to abandon all unsaved changes.

Neutralize

There may be occasions when the scanned image is tinted with an undesirable hue. In order to rectify this problem, click the Neutralization button, which invokes a color adjustment wheel (similar to Color Adjustment color wheel).

From the previewed image on sample 1 or sample 2, choose the grayscale or black and white pixel and click on it by using the dropper cursor. The whole image will recover to its original image without tint on it. Grayscale and black and white pixel usually are the standard value for this tool to compare with the tainted scanned image. In this way, the image can be correct.

Operation:

1. Click on the Neutralization tab on the Enhancement Tool dialog box.
2. Click on the Picker.
3. Place the picker to sample 1 or 2 and click on the desired pixel. The image will be repainted.
4. While holding on the mouse button, you can move the mouse cursor on the sample graphic to choose any point, the sample image will be updated simultaneously. You can release the mouse button at any time if you choose the right point.
5. Select the "OK" button to accept all the changes or the "Cancel" button to abandon all unsaved changes.

To give up the picker, simply click your mouse outside the sample.
Color Adjustment

This option allows you to control the distribution of color by means of saturation or dilution of a particular color.

The dialog box displays a continuous color spectrum on a wheel. By clicking on certain areas of the wheel, "Sample 1" changes to a particular hue which governs the distribution.

Operation:

1. Set the brightness of color by adjusting the triangle below the lightness bar beneath the color wheel.
2. Position and drag the cursor at any point on the color wheel to select the desired hue and saturation of the image.
3. Click on the "Reset" button to return to the default diagonal as in the original.
4. Select "OK" to accept all the changes or the "Cancel" button to abandon all unsaved changes.

Color Balance

This option allows you to change the mixture of colors in a color image. You can use this option to emphasize certain colors or to diminish unwanted ones.

Selection of the Shadow, Highlight, or Midtone check boxes in the dialog box let you focus the color balance changes on three different brightness levels. The three triangular sliders on the color bars allow you to adjust the color balance in one or more of the 3 color (RGB) channels.

Operation:

1. Click on the Color Balance button to display the Enhancement dialog box for color balance.
2. Select one of the Shadow, Midtone or Highlight check boxes to modify colors in that spectrum.
3. Click on a triangular slider on one of color bars and move to the desired position. Alternatively, enter a value between -100 and 100 in the edit boxes beside the color bars.
4. Click on the "Reset" button to return the Tonal Map to the default diagonal as in the original.
5. Select "OK" to accept all the changes or the "Cancel" button to abandon all unsaved changes.

Invert

This function inverts all the tone values such that each color in the original is exchanged with its color complement. This effect is similar to using the Tonal Map to tonally invert the image.

Normal Image | Inverted Image