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GMImage.Threshold

Threshold image channels (below threshold becomes black, above threshold becomes white).

Component Version macOS Windows Linux Server iOS SDK
GraphicsMagick 2.0 ✅ Yes ✅ Yes ✅ Yes ✅ Yes ✅ Yes
MBS( "GMImage.Threshold"; ImageRef { ; threshold } )   More

Parameters

Parameter Description Example Flags
ImageRef The image reference number. 1
threshold The range of the threshold parameter is 0 to MaxRGB (65535). 127*256 Optional

Result

Returns "OK" on success.

Description

Threshold image channels (below threshold becomes black, above threshold becomes white).

Examples

Applies a threshold on the image:

Let ( [
$Image = MBS("GMImage.NewFromContainer"; GraphicsMagick::image);
$Result = MBS("GMImage.Threshold";$Image; 127);
$Result = MBS("GMImage.WriteToJPEGContainer"; $Image);
$Error = MBS("GMImage.Release";$Image)
];
$Result)

Convert image to 1 bit TIFF:

# Load from container
Set Variable [ $Image ; Value: MBS("GMImage.NewFromContainer"; GraphicsMagick::image); ]

# make black and white with threshold
Set Variable [ $Result ; Value: MBS("GMImage.Threshold";$Image; 127); ]

# mark as monochrome image
Set Variable [ $Result ; Value: MBS("GMImage.SetMonochrome";$Image; 1); ]

# set type to 1 for black/white
Set Variable [ $Result ; Value: MBS("GMImage.SetType";$Image; 1); ]

# set to use TIFF for compression
Set Variable [ $Result ; Value: MBS("GMImage.SetMagick";$Image; "TIFF"); ]

# set to use CCITT 4 Fax compression
Set Variable [ $Result ; Value: MBS("GMImage.SetCompressType";$Image; 4); ]

# and write to a file
Set Variable [ $Result ; Value: MBS("GMImage.WriteToFile"; $Image; "/tmp/test.tif"); ]

# cleanup
Set Variable [ $Error ; Value: MBS("GMImage.Release";$Image) ]

Make a picture black and transparent:

Set Variable [$image; Value:MBS( "GMImage.NewFromContainer"; Test::BigImage)]
Set Variable [$r; Value:MBS( "GMImage.Threshold"; $image; 127)]
Set Variable [$imagecolor; Value:MBS( "GMImage.Transparent"; $image; "white")]
Set Field [Test::Result; MBS( "GMImage.WriteToPNGContainer"; $image;)]
Set Variable [$Error; Value:MBS("GMImage.Release";$image)]

See also

Example Databases

Blog Entries

This function checks for a license.

Created 18th August 2014, last changed 25th February 2026


GMImage.Texture - GMImage.TotalColors