Acorn Acorn 7

Color Adjustment Filters

Many of the filter definitions below come directly from Apple’s core image filter reference. 

1bit:  Converts all pixels in your image to either black or white.

Alpha Multiply:  Multiplies the alpha values of your pixels by a certain amount.  Can be useful for sharpening anti-aliased edges of shapes and text.

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Original image

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Color Controls: Brightness decreased

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Color Controls:  Saturation increased

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Color Controls: Saturation decreased

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Exposure Adjust: Exposure decreased

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Gamma Adjust:  Power decreased



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Hue Adjust

Color Controls:  Adjusts saturation, brightness, and contrast values.

Saturation:  Saturation is the intensity of color in your image. If you slide the slider to the left (to 0), the image will become black and white, and if you slide it to the right (2.00) it will become fully saturated.

Brightness:  Adjust the darkness or lightness in your image.  Drag the slider all the way to the left your image will become totally black, if dragged to the right it will become completely white. 

Contrast:  Contrast is the difference between the lights and darks of your image. A higher contrast will have darker darks and lighter lights.  A lower contrast or no contrast will make the tones in the image appear the same.

Curves: See Curves.

Dither:   Dither your layer with a drop down menu to choose from Atkinson (old school Mac OS), Floyd Steinberg, Gaussian Blue, and Ordered Reproducible.  

Exposure Adjust:  Adjusts the exposure setting for an image similar to the way you control exposure for a camera when you change the F-stop.  This filter multiplies the color values to simulate exposure change by the specified F-stops.

Gamma Adjust:  Adjusts midtone brightness.  This filter is typically used to compensate for nonlinear effects of displays.  Adjusting the gamma effectively changes the slop of the transition between black and white. Gamma Adjust leaves blacks and whites unchanged, while adjusting the mid-point colors of your image.  A high gamma level can create a washed out appearance to an image, but a small adjustment usually creates a pleasing result.  

Grayscale:  Turns a colored image into grayscale.  See Black & White.

Hue Adjust:  Changes the overall hue, or tint, of the source pixels.  This filter essentially rotates the color cube around the neutral axis. This filter adjusts the color of your image, leaving black, white, and gray alone. There is a dial to adjust the color of your image. Think of the dial as a compass. If the dial is placed south, it will show your original image, to the west and it will become red, north for blue, and east for green.

Levels:  See Levels.

Mask to Alpha: Converts a grayscale image to a white image that is masked by alpha. The white values from the source image produce the inside of the mask; the black values become completely transparent. With the Invert Colors option, Mask to Alpha will convert the white areas of the image to transparent, and keep the black opaque. This is helpful for scanned line drawings to make the backgrounds transparent.

Remove Color Cast: Adjust the exposure and choose a color to remove in your image to be replaced with white.  This is useful for images taken indoors that are excessively yellow.  

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Remove Color Cast Filter

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Replace Color:  Choose a specific color to remove and replace it with another.  Adjust the tolerance as needed.

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Transparentomatic: Remove a specific color in your image and replace it with transparency.



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Vibrance: Adjusts the saturation of an image while keeping pleasing skin tones.

White Point Adjust: Adjusts the reference white point for an image and maps all colors in the source using the new reference. The White Point Adjust filter determines what "white" is in your photo. Light isn't usually really white. It can have tints of yellow, orange, or blue. The true color of white depends on the lighting when the photo was taken. For best results choose a natural color that is close to white.




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Try playing around with some of the filters and experiment, experiment, experiment.  For more information, check out the Tutorials or send an email to and request a tutorial.

Additional Relevant Documentation  

Filters Basics (video tutorial)

Filters Basics