Use the Gamma Correction command to adjust the brightness and contrast of an image in unison. The gamma of an image is a standard measure of its contrast and brightness.

The gamma curve has three components:

The red, green, and blue of the image. In addition to adjusting the brightness and contrast of the image, with the Gamma Correction command you can adjust the color balance of an image by unlinking the three components and changing them separately. For example, if the image has a red cast to it, you can reduce its red value.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image).

To use the Gamma Correction command:

To limit the adjustment to a specific area, make a selection in the image.

Choose Adjust > Brightness and Contrast > Gamma Correction.
In the Gamma Correction dialog, the graph shows the gamma curves for the three colors. If the three colors have the same gamma value, there is one white line representing the three colors. If the gammas are different values, there is a line for each color.
The left side of the graph represents the shadows of the image; the right side represents the highlights.

Do one of the following:

To adjust the brightness and contrast in unison, mark the Link check box.

To change the color balance of the image rather than the brightness and contrast, clear the Link check box.

For the Red, Green, and Blue values, drag the sliders or type new numbers in the edit boxes. A value of 1 indicates the original gamma. If colors are linked, increasing the value lightens the image and decreasing the value darkens the image. If colors are not linked, increasing or decreasing a individual color value increases or decreases the amount of that color in the image.

Click OK.

Note: The Gamma Correction command can result in an image looking somewhat flat; you may want to increase the contrast after correcting the gamma.

Use the Highlight/Midtone/Shadow command to separately adjust the light, middle, and dark values (the tonal values) of a photograph.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image).

To use the Highlight/Midtone/Shadow command:

To limit the adjustment to a specific area, make a selection in the image.

Choose Adjust > Brightness and Contrast > Highlight/Midtone/Shadow.

To adjust values in relation to each other, select:

Linear adjustment method

Each value ranges from 0 to 100 and defaults are 0 for Shadow, 50 for Midtone, and 100 for Highlight. To adjust values independently

Dynamic adjustment method

Each value ranges from -100 to 100 and zero represents no change for that value.

Adjust these tonal values:

Shadow

Removes lightness proportionally to the image. Increasing the value from zero darkens lighter pixels.

Midtone

Changes the middle portion of the light scale. Increase the value to darken middle values or decrease the value to lighten middle values.

Highlight

Adds lightness proportionally to the image. Decreasing the value from 100 lightens darker pixels.

Click OK.

Use the Levels command to make adjustments to the brightness, contrast, and gamma in the image. Adjusting the gamma changes the brightness values of middle grey tones.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image).

To use the Levels command:

To limit the correction to a specific area, make a selection in the image.

Do one of the following:

To modify the image pixels directly, choose Adjust > Brightness and Contrast > Levels.

To create a Levels adjustment layer, choose Layers> New Adjustment Layer > Levels.

In the Channel drop-down list, select a color channel to edit. Choose RGB to edit the red, green, and blue channels together. Choose Red, Green, or Blue to edit the individual color channels.

To increase the contrast of the image, drag the Input levels sliders, which show the image’s brightness values. To darken the darkest values, drag the black diamond to the right; all values below this value become zero (black). To lighten the lightest values, drag the clear diamond to the left; all values above this value become 255 (white). To change the value of medium grey, drag the grey Gamma diamond left or right; the range for of the gamma value is 0 to 7.99, with 1 being in the middle.

To decrease the contrast, drag the Output levels sliders. To lighten the darkest pixels, drag the black diamond to the right. To darken the lightest pixels, drag the clear diamond to the left.

Click OK.

Use the Hue Map command to replace one or more colors throughout a photograph or other complex image. For example, you can shift all greens to blues.

You can also use the Hue Map command to change the saturation or the lightness of the image. When you adjust these values, all colors (original and shifted colors) are adjusted.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image).

To use the Hue Map command:

To limit the correction to a specific area, make a selection in the image.

Choose Adjust > Hue and Saturation > Hue Map.
The Hue Map dialog opens. In the Hue shift group box, the top row of color boxes shows 10 original colors and the bottom row of color boxes represents the shifted colors. Each color is represented in degrees around the 360-degree color wheel.

To reset the colors to their default settings (which is no shift in colors), in the Presets drop-down list choose Default.

For each color that you want to shift, drag its slider to a new color.

To change the saturation of all colors, adjust the Saturation shift value (from -100 to 100). A value of zero represents no change.

To change the lightness of all colors, adjust the Lightness shift value (from -100 to 100). A value of zero represents no change.

Click OK.

Use the Colorize command to replace all colors in a selection or an image with a single color and saturation while leaving the lightness values unchanged. You can use this command to create sepia tones (the brown seen in old photographs) and other single-color effects.

Note: The Colorize command creates an image that looks like a duotone (two-color) image. To create a duotone with more subtle color changes, apply the Greyscale command, increase the color depth to 16 million (24-bit) colors, then apply the Colorize command.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image).

To colorize an image:

To limit the correction to a specific area, make a selection in the image.

Choose Adjust > Hue and Saturation > Colorize.

To colorize the image, modify the following settings:

Hue

The hue that all current colors are changed to. Click the slider button and drag the slider to select the color visually.

Saturation

The saturation of the selected hue. Click the slider button and drag the slider to select the saturation visually.

Click OK.

In Paint Shop Pro you can reduce or remove colors in several ways. You can create black-and-white, greyscale, duotone (two-color), colorized, and sepia images. You can also create a negative image or create a positive image from a photographic negative.

Ways to reduce or remove colors:

Creating Black and White Images

To create a black-and-white image, use the Threshold command.

Creating Greyscale Images

A greyscale image looks like a traditional black-and-white photograph.

Creating Sepia-Tone Images

Sepia tones are the browns of old black-and-white photographs and newsprint.

Reducing the Number of Lightness Levels

Use the Posterize command to reduce the number of lightness levels in the image and create interesting effects.

Creating Negative Images

Use the Negative Image command to replace each pixel color with its opposite on the color wheel, use an Invert adjustment layer command to create an adjustment layer that has the same effect as the Negative Image command but doesn’t change the original image pixels, or use the Solarize command to produce a negative image in which you control the threshold level.

Changing Individual Colors You can also use the Hue Map command to change the saturation or the lightness of the image. When you adjust these values, all colors (original and shifted colors) are adjusted. For example, you can shift all greens to blues.

Colorizing Images

Use the Colorize command to replace all colors in a selection or an image with a single color and saturation while leaving the lightness values unchanged. You can use this command to create sepia tones (the brown seen in old photographs) and other single-color effects.

To create a black-and-white image, use the Threshold command. Select the threshold lightness value—below which all pixels are changed to black and above which all pixels are changed to white. This command does not change the color depth of the image.

Note: The Threshold command creates an image with pixels of two colors: Black or white. To create a “black-and-white” photograph, which is really made up of many shades of grey. You can also decrease an image’s color depth to 2 colors, which gives you options for how colors are reduced that may result in more natural-looking images than the Threshold command.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image). In addition, adjustment layers are available for 16 million(24-bit) color or greyscale images only.

To use the Threshold command:

To limit the correction to a specific area, make a selection in the image.

Do one of the following:

To modify the image pixels directly, choose Adjust > Brightness and Contrast > Threshold.

To create an adjustment layer, choose Layers> New Adjustment Layer > Threshold.

Click the Zoom out button until you can see the entire image in the preview windows.

In the Threshold edit box, select a pixel lightness value that determines which pixels change to white (those above the threshold) and which pixels change to black (those below the threshold). The value ranges from 1 to 255. Adjust the threshold until the image in the preview window is satisfactory.

Click OK.

A greyscale image looks like a traditional black-and-white photograph. Use the Greyscale command to convert a colored image into a greyscale image with a palette that contains white, black, and 254 shades of grey. Each color in the image is replaced with a grey that matches its lightness value.

The Greyscale command changes the color depth of the image to 8-bit.

To create a greyscale image:

Choose Image > Grey Scale.

Sepia tones are the browns of old black-and-white photographs and newsprint. You can give your photographs and graphics the 19th century look by turning them into sepia-tone images. In Paint Shop Pro you have two ways to do this:

Apply the Sepia Tone effect to the image. You select the number of years to age the image.

Use the Colorize command and choose a brown hue.

• There’s another way to create an image that looks like a greyscale but maintains its same color depth: Use the Channel Mixer command and mark the Monochrome check box. With this command you can modify how much of the image’s red, green, and blue channels are used to create the monochrome image.

Use the Posterize command to reduce the number of lightness levels in the image and create interesting effects. With this command, Paint Shop Pro divides the range of lightness levels (from 2 to 255) into a number of equal increments that you specify. As you lower the number, you increase the effect.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image). In addition, adjustment layers are available for 16 million(24-bit) color or greyscale images only.

To use the Posterize command:

To limit the correction to a specific area, make a selection in the image.

Do one of the following:

To modify the image pixels directly, choose Effects > Artistic Effects > Posterize.

To create a Levels adjustment layer, choose Layers> New Adjustment Layer > Posterize.

In the Levels edit box, select the number of lightness levels (2 to 255) for the adjusted image. To create a dramatic effect, the number of levels typically must be below 10.

Click OK.

In Paint Shop Pro there are three ways to create a negative image (which looks like a photographic negative):

Use the Negative Image command to replace each pixel color with its opposite on the color wheel. You can also use the Negative Image command to create a positive image from a scanned photographic negative.

Use an Invert adjustment layer command to create an adjustment layer that has the same effect as the Negative Image command but doesn’t change the original image pixels.

Use the Solarize command to produce a negative image in which you control the threshold level. This level is the lightness value above which all colors are inverted. Use this command to create interesting effects.

You can create a negative of a selection or an entire image.

Important: To apply this command to a selection, the image must be a 16 million(24-bit) color image (otherwise the command is applied to the entire image). In addition, adjustment layers are available for 16 million(24-bit) color or greyscale images only.

To use the Negative Image command:

Choose Adjust > Negative Image.

To use an Invert adjustment layer:

Choose Layers > New Adjustment Layer > Invert.

Choose the layer properties; there are no additional settings for the adjustment layer.

Click OK.

To use the Solarize command:

Choose Effects > Artistic Effects > Solarize.

In the Threshold edit box, select a lightness threshold (1 to 254) above which all colors are inverted. At a threshold of 1, all image pixels are inverted and the effect is the same as applying the Negative Image command.

Click OK.

The histogram displays a graph of the distribution of red, green, blue, greyscale, hue, saturation, and lightness values in an image. You can analyze the distribution of detail in the shadows (shown in the left part of the histogram), in the midtones (shown in the middle), and the highlights (shown in the right part) and decide how to make corrections.

After you analyze the histogram, you can correct the image with Paint Shop Pro’s color and contrast correction commands or you can use commands that adjust your image based on its histogram features: Equalize, Histogram Adjustment, and Stretch.

Do I need the histogram? For image editing professionals, the histogram is a powerful tool for understanding and correcting images. For casual users, getting familiar with the histogram may not be necessary. Paint Shop Pro offers many simpler ways to adjust images.

To display the histogram for an image:

To limit the histogram data to a specific area, make a selection in the image.

Choose View > Palettes > Histogram or press F7.

The graph represents how many pixels are at each value of the selected channels. The vertical axis represents the number of pixels and ranges from zero pixels to the highest number of pixels in the graph. The horizontal axis represents the value from zero to 255 of a selected channel: Red, Green, Blue, Greyscale, Hue, Saturation, and Lightness.

Mark or clear the check boxes below the graph to display or hide the values for the channels.

Choose the image data that is graphed:

Sample merged

If this check box is marked, the histogram graphs all layers in the image. If this check box is cleared, the histogram graphs only the current layer.

Selection only

If this check box is marked, the histogram graphs only the active selection. If the check box is cleared, the histogram graphs the entire layer or image.

Do one of the following:

To view information about a specific value, place the cursor at that point on the histogram.

To select a range of values, click and drag in the graph. When you release the mouse, the range is deselected.

These fields show information about the selected point or range

Value(s)

The value or range of values (from 0 to 255) of the point over which the cursor is positioned in the graph.

% in Range

The percent of image pixels that are the value(s) of the selected point or range. The number in parentheses is the number of pixels that are the selected value(s).

% Above

The percent of image pixels that are above the value(s) of the selected point or range.

% Below

The percent of image pixels that are below the value(s) of the selected point or range.

To view the mean and median values for a channel, in the Display channel drop-down list choose a channel: Red, Green, Blue, Hue, Saturation, Lightness, or Greyscale. The Mean field displays the average value for the selected channel. The Median field displays the middle value in the range of values for the selected channel.

Note: The Display Channel has no effect on what is graphed in the histogram and also does not affect the four statistics immediately below it.

The value of a selected channel is graphed from 0 to 255 along the horizontal axis of the histogram. The meaning of the value depends on the selected channel:

Red, Green, and Blue values represent the amount of red, green, or blue in each color channel. A channel value of zero indicates the color is not present and a value of 255 indicates the color is at full strength. For example, if the graph has a spike at the value 128 for the Red channel, then there are a large number of pixels with a red value of 128 (or middle red).

Hue, Saturation, and Lightness values are a different representation of color than the Red, Green, and Blue channels. Hue is the actual color and the value is the number assigned on the color wheel; for example, red is zero, yellow is 43, green is 85, cyan is 128, blue is 170, and magenta is 212. (As a reference, look at the color wheel on the Jasc Color Picker.) Saturation is the level of grey added to the hue; zero is very grey and unsaturated and 255 is no grey and fully saturated. Lightness is the brightness of the hue; zero is no light (black), 128 is middle grey, and 255 is fully light (white). The lightness histogram has information similar to the greyscale histogram.

Greyscale values are levels of grey; zero is black, 128 is middle grey, and 255 is white. These represent the brightness or luminosity of an image. The distribution of grey values determines the contrast of an image.

Here are guidelines that can help you analyze the histogram and make decisions about how to correct your images:

If a line spikes, there are many pixels at that value.

If a line is close to the horizontal axis, there are few pixels at that level.

If the graph is spread out, the image has a balanced composition and probably has enough detail to be corrected.

If the lines are compressed into a narrow area, the image probably doesn’t contain enough detail to be corrected; try a new scan or find another picture.

The usefulness of the histogram depends upon the image content as well as its channel values. For example, an image of pale, desaturated skin tones may display a big saturation peak on the left side (in the lower values) of the histogram. An image of a bright red fire engine may display a peak on the right side (in the higher values) of the histogram. If the images were improperly saturated, the saturation histograms might be reversed.

If the greyscale graph is mostly at the left side, the image is too dark.

If the greyscale graph is mostly at the right side, the image is too light.

If the greyscale lines are not spread out enough, you may need to increase the contrast.

Use the Histogram Adjustment command to adjust the contrast and color balance of your image. The Histogram Adjustment dialog graphs one color channel at a time, unlike the Histogram Window which can display all color channels at once. You may want to first display the Histogram Window (choose View > Palettes > Histogram), then use autoproofing on the Histogram Adjustment dialog so you can see changes graphed in the Histogram Window.

Important: This command applies to greyscale and 16 million (24-bit) color images only.

Note: When you place the cursor over the histogram, a ToolTip displays the following information: Input is the value on the horizontal axis, Count is the number of pixels that have that value, Integral is the percentage of pixels in the image with that value, and Output is the adjusted value.

The graph in the Histogram Adjustment dialog displays how many pixels are at each value of the selected channel. The vertical axis represents the number of pixels and ranges from zero pixels to the highest number of pixels in the graph. The horizontal axis represents the value from zero to 255 of the selected channel.

When you change the histogram, the graph displays the adjusted his­togram as red and the original histogram as grey. To turn off the red overlay, clear the Overlay result histogram check box.

In the Histogram Adjustment dialog, you can edit the luminance (lightness) and the red, green, and blue color channels. The Histo­gram Window (opened by choosing View > Palettes > Histogram) also graphs the hue, saturation, and greyscale values, but these can­not be edited by adjusting the histogram.

To use the Histogram Adjustment command:

To limit the adjustment to a specific area, make a selection in the image.

Choose Adjust > Brightness and Contrast > Histogram Adjustment to open the Histogram Adjustment dialog.

Click to magnify the histogram or click to reduce the view of the histogram. Click 1:1 to display the histogram at its original size.

For the Edit option, choose a channel:

Luminance

Lightness values of the image. If you are correcting contrast, start with this channel.

Color

Pick a color channel from the drop-down list: Red, Green, or Blue.

In the Presets drop-down list, choose Default. The default values represent no adjustment to the image.

On the left side of the histogram, look for a gap between the left edge and the point where the graph starts to rise. If there is a gap, it shows that the darkest pixels in the image are not completely black. Click and drag the Low slider (the black triangle) to the point where the graph rises. The top Low edit box displays the low position (from 0 to 255). The bottom edit box displays the percentage of pixels that are between zero and the low value; their contrast will be lost. As a general rule, keep the percentage below 0.1%.

On the right side of the histogram, look for a gap between the right edge of the window and the point where the graph decreases to zero pixels. If there is a gap, click and drag the High slider (the white triangle) to that point on the graph. This changes the lightest pixels in the image to white. As a general rule, keep the High percentage change (the bottom edit box) to below 0.1%.

If the overall image is too dark or too light, adjust the gamma. (Gamma is a standard measure of change in an image’s contrast.) If the image is too dark, drag the Gamma slider (the grey triangle) to the right to increase the gamma (the number changes in the Gamma edit box). If the image is too light, drag the Gamma slider to the left to decrease the gamma.

If the graph has peaks on the left and right sides and contains low points in the center, the midtones need to be compressed. Shadows and highlights need to be expanded to reveal the information they contain. This often occurs in flash photography when a subject is too close to the camera; the subject appears brightly illuminated but the background of the photograph is very dark. To compress the midtones, click and drag the Midtones slider up.

If the graph peaks in the center and has a low number of pixels at the left and right sides, expand the midtones by dragging the Midtones slider down.

If you are improving your image, skip this step. If you are creating artistic effects, use the Output Max and Min sliders on the left side of the histogram to make further adjustments. The Max slider is the white circle within a grey square; the Min slider is the black circle within a grey square. To darken the image’s whites, click and drag the Max slider down. To lighten the image’s blacks, click and drag the Min slider up.

Note: Even though you are dragging sliders along the vertical axis, the Max and Min values actually affect the horizontal axis. They indicate the maximum and minimum value (from 0 to 255) in the image. All pixels outside those values are converted so that they fall within the maximum and minimum.

To adjust another color component, choose it in the Edit drop-down list and follow these steps again.

Click OK.