Monkeybread Software - MBS FileMaker Plugin: GMImage.MultiplyChannel

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GMImage.MultiplyChannel

Multiplies all values in a channel.

Component	Version	macOS	Windows	Linux	Server	FileMaker iOS SDK
GraphicsMagick	5.0	Yes	Yes	Yes	Yes	Yes

MBS( "GMImage.MultiplyChannel"; ImageRef; Channel; Factor { ; Add1; Add2 } ) More

Parameters

Parameter Description Example Flags

ImageRef The image reference number. 1

Channel Which channel to work with. Can be opacity, red, green or blue. The value rgb will apply effect to all three color channels. "rgb"

Factor The multiplication factor. Range from -1.0 to 1.0. 0.1

Add1 The value to add before multiply. Usually between -65535 and 65535. 0 Optional

Add2 The value to add after multiply. Usually in range from -65535 to 65535. 65535*0.9 Optional

Parameter	Description	Example	Flags
ImageRef	The image reference number.	1
Channel	Which channel to work with. Can be opacity, red, green or blue. The value rgb will apply effect to all three color channels.	"rgb"
Factor	The multiplication factor. Range from -1.0 to 1.0.	0.1
Add1	The value to add before multiply. Usually between -65535 and 65535.	0	Optional
Add2	The value to add after multiply. Usually in range from -65535 to 65535.	65535*0.9	Optional

Result

Returns OK or error.

Description

Multiplies all values in a channel.
For every pixel component, we apply the formula:
newValue = ((Add1 + oldValue) * Factor) + Add2
This can be used to change brightness or make opacity less/more transparent.

Examples

Multiplies existing opacity channel to make image 90% transparent:

// existing values * 0.1 and add 90% to the value to move to higher range.
MBS("GMImage.MultiplyChannel"; $ImageRef; "opacity"; 0.1; 0; 255*0.9)

Invert image via multiply:

Set Variable [ $image ; Value: MBS( "GMImage.NewFromContainer"; Invert::Input ) ]
# each channel...
// Set Variable [ $r ; Value: MBS( "GMImage.MultiplyChannel"; $image; "red"; -1; 0; 65535) ]
// Set Variable [ $r ; Value: MBS( "GMImage.MultiplyChannel"; $image; "green"; -1; 0; 65535) ]
// Set Variable [ $r ; Value: MBS( "GMImage.MultiplyChannel"; $image; "blue"; -1; 0; 65535) ]
# all channels...
Set Variable [ $r ; Value: MBS( "GMImage.MultiplyChannel"; $image; "rgb"; -1; 0; 65535) ]
Set Field [ Invert::Output ; MBS( "GMImage.WriteToPNGContainer"; $image; "output.png") ]
Set Variable [ $r ; Value: MBS( "GMImage.Release"; $image) ]

Example Databases

Blog Entries

Release notes

Version 8.4
- Fixed GMImage.MultiplyChannel for 16-bit colors.

Created 3th February 2015, last changed 11st November 2019

GMImage.MotionBlur - GMImage.Negate

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