Monochrome

This transformation lets you convert a color image to a monotone image. It operates in four stages, any of which you can omit if it is not needed. The tabs at the bottom of the dialog box let you control the settings for each stage.

Amount

The amount control lets you control how much of the monochrome transformation is applied to the input image. You can apply a percentage of the transformation to the entire image, or you can specify an amount mask to restrict the effects of the transformation to only part of the input image.

Stage 1: Convert

The first stage is conversion to black and white, which you can accomplish using any of four different methods.

All four  methods include an Exposure slider that can brighten or darken the result image to use the full dynamic range without clipping. You can use the Show Clipped Highlights tool bar  at the top of the screen to highlight clipped highlights in the black and white image. If the image is too bright, dial back the Exposure slider.

Method 1: Extract Channel

This method extracts a single channel from the color image to produce a black and white result. This is the simplest but least flexible method. The Exposure slider lets you lighten or darken the image as necessary. The channels you can extract are: luminance, HSV-V, HSL-L, red, green, blue, cyan, magenta, yellow, or white.

The luminance channel is the default method of converting color to black and white – luminance is a weighted average of red, green and blue based on the relative sensitivity of the eye to each color.

The HSV-V and HSL-L channels correspond to the image brightness in the HSV and HSL color spaces. In the HSV color space, if any channel is maxed out, the brightness is considered 100%. In the HSL color space, only pure white is 100%. Black is 0% in either color space.

Selecting one of the red, green, blue channels simply gives you the information in that one channel.

Selecting cyan gives you the average of the blue and green channels, magenta gives you the average of the red and blue channels and yellow gives you the average of the red and green channels.

Selecting white gives you the average of all three channels.

Method 2: Filter

The filter method is like photographing a color scene on black and white film through a colored filter. You select a filter color (or color image) to emphasize some colors in the input image over others. As a rule of thumb, if you want a color to come out lighter, use a filter of the same color; if you want to make it come out darker, use a filter of the complementary color.

Method 3: Channel Mixer

The channel mixer method computes a weighted sum of the red, green and blue channels. While this interface is less intuitive than the filter method, it allows for the possibility of negative weights which do not correspond to any physically realizable color filter. This can be useful when trying to achieve more extreme effects than you can get with the filter method, such as very dark skies or simulated infrared.

Method 4: Hue Curve

The hue curve method lets you lighten or darken the result image according to the hue of the input image by specifying a hue curve. This method is the most complicated, but it gives you the most control. If the curve is a horizontal line through the middle of the curve area, all hues have no brightness change. Creating control points on the curve that cause it to be pass above the horizontal center line lighten the pixels of the corresponding hues in the image. Dragging the curve below the center line darkens them. The hue histogram in the curve background gives you an idea where on the hue curve different parts of the image fall. The Strength slider below the hue curve lets you either increase or decrease the strength of the lightening or darkening to reduce or exaggerate the overall effect.

The Strength slider amplifies or attenuates the brightness changes specified by the hue curve.

Stage 2: Curve

The second stage applies a brightness curve to the result of stage 1. You can use the curve to adjust the brightness, contrast, and dynamic range of the black and white image

Stage 3: Texture

The third stage applies texture to the result of stage 2. You can use this to create simulated film grain or other effects.

Texture

The texture control lets you select a texture image. A variety of film grain, mezzotint and other textures are supplied with Picture Window, but any 8- or 16-bit black and white image that can be seamlessly tiled will work.

Texture Strength

This slider increases or decreases the amount of text that is applied to the image.

Texture Scale

This slider enlarges or shrinks the size of the texture making it coarser or finer.

Stage 4: Tint

The fourth stage tints the result of stage 3. This is like the Tint transformation as it uses a color line control to define the colors to which each brightness level is assigned.

  Output Bit Depth

This control lets you control the bit depth (either 8-bit or 16-bit) of the black and white output image created from 24-bit color input images. Since the conversion from color to black and white generally averages the red, green and blue channels with various weights, unless you are extracting the red, green or blue channel, the resulting black and white image contains more than 8 bits of information.

This control is only displayed if the input image is 24-bit color. If the input image is 48-bit color, the output is always a 16-bit black and white image.

If you choose to tint the image in stage 4, 8-bit black and white images become 24-bit color and 16-bit black and white images become 48-bit color.

  Base Histogram on Masked Area Only

The curve controls (both for adjusting hue and brightness) display both a histogram and a curve. If this button is raised, the histograms are based on the entire input image. If depressed, the histograms are based on just the currently masked area as defined by the amount mask. If there is no mask, the histograms are based on the entire image. If there is a mask but it is entirely black, the histograms are not displayed. Changing this setting only affects the way histograms are displayed and has no effect on the output image.

If you are using a mask to limit the action of the transformation to just part of the image, this control lets you see the histograms of just the part you are adjusting.

Probes

In Convert mode, clicking on the input image displays a red marker on the hue curve, if any. Shift-clicking on the input image creates a new control point on the curve corresponding to the hue at the point you clicked.

In Curve mode, clicking on the input image displays a red marker on the brightness curve, if any. Shift-clicking on the input image creates a new control point on the curve corresponding to the brightness at the point you clicked.

In Tint mode, clicking on the input image displays a red marker on the color line, and shift-clicking on the input image inserts a new control point in the color line.

The probe is disabled in Texture mode.

Probes act on the result of the previous operation (or on the input image if there is no previous operation). Thus clicking on the input image in Tint mode picks up the brightness the image with Curve and Convert mode settings applied.                                                   

Settings Menu

HSV/HSL

This setting selects the HSV or HSL color space when using the Hue Curve method in stage 1. It does not affect any other aspect of the monochrome transformation. If HSV is selected, the HSV hue histogram is displayed in the curve control and the curve adjusts HSV hue. If HSL is selected, the HSL histogram is displayed and the curve adjusts HSL hue.