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gui:image:type [2019/04/12 13:13] (current)
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 +====== Type ======
 +
 +**Use this submenu to determine the type of the active image or to convert it to another type.**
 +
 +==== 8-bit ====
 +
 +Converts to 8-bit grayscale. The active image must be 16-bit grayscale, 32-bit grayscale, 8-bit color or RGB color.\\ ImageJ converts 16-bit and 32-bit images to 8-bits by linearly scaling from min-max to 0-255, where min and max are the two values displayed in the **Image>​Adjust>​Brightness/​Contrast** command. The command **Image>​Show Info** displays these two values as the "​Display range"​. Note that this scaling is not done if "Scale When Converting"​ is not checked in **Edit>​Options>​Conversions**. With stacks, all the slices are scaled to 8-bits using the min and max of the currently displayed slice. \\ RGB images are converted to grayscale using the formula:
 +
 +   gray = 0.299 * red + 0.587 * green + 0.114 * blue
 +
 +or the formula:
 +
 +  gray = (red + green + blue) / 3
 +
 +if "​Unweighted RGB to Grayscale Conversion"​ is checked in **Edit>​Options>​Conversions** (ImageJ 1.32g or later).
 +
 +==== 16-bit ====
 +
 +Converts to unsigned 16-bit grayscale. The active image must be grayscale (8 or 32-bit) or RGB color.
 +
 +==== 32-bit ====
 +
 +Converts to signed 32-bit floating-point grayscale. The active image must be grayscale (8 or 16-bit) or RGB color.
 +
 +==== 8-bit Color ====
 +
 +Converts to 8-bit indexed color using Heckbert'​s median-cut color quantization algorithm. A dialog box allows the number of colors (2-256) to be specified. The active image must be RGB color.
 +
 +==== RGB Color ====
 +
 +Converts to 24-bit RGB color. The active image must be grayscale, 8-bit Color, or an RGB (red, green, blue) or HSB (hue, saturation and brightness) stack.
 +
 +==== RGB Stack ====
 +
 +Converts an image into a 3-slice (red, green, blue) stack. The active image must be RGB color.
 +
 +==== HSB Stack ====
 +
 +Converts to a 3-slice (hue, saturation and brightness) stack. The active image must be RGB color.
 +
 +Note that the RGB to HSB and backwards conversion are not completely reversible due to some rounding errors when storing the result in 8-bit integers.
 +
 +Applying the following macro to a RGB image results in an image that is not identical to the orginal (the differences are tiny, though).
 +
 +  run("​HSB Stack"​);​
 +  run("​RGB Color"​);​
 +
 +An attempt to perform an unsupported conversion causes a dialog box to be displayed that lists the possible conversions.
 +
 +{{{{:​gui:​image:​type-conversations.gif|}}|Image type conversions}}
 +
 +The * indicates that both single images and stacks can be converted.
  
gui/image/type.txt ยท Last modified: 2019/04/12 13:13 (external edit)