The script for deleting empty alpha channels.

[alinaj84027284]

Hello.
Please help me create a script that removes empty alpha channels.
That is, the ones that have a solid color 0 0 0.

That is, I select the alpha channel and if it is empty 0 0 0 0 by RGB, it is deleted.
If not, nothing happens.

I'm not good at scripting, so I'm asking for help.

Thank you very much.

[Bojan Živković]

@jazz-y @Stephen_A_Marsh @c.pfaffenbichler @r-bin @Kukurykus maybe can help you with that task.

[jazz-y · Accepted solution]

Try this: check if channel have pixels or not script code 

[Stephen_A_Marsh · Accepted solution]

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@alinaj84027284 wrote:

I'm not good at scripting, so I'm asking for help.

Thank you very much.

---

@alinaj84027284 – Here is the code recommended by @jazz-y based on the original code from @c.pfaffenbichler

// 2022, use it at your own risk;
if (app.documents.length > 0) {
    var myDocument = app.activeDocument;
    var theChannels = myDocument.channels;
    var originalRulerUnits = app.preferences.rulerUnits;
    app.preferences.rulerUnits = Units.PIXELS;
    var theTotal = Number(myDocument.width) * Number(myDocument.height);
    for (var m = theChannels.length - 1; m >= 0; m--) {
        var thisChannel = theChannels[m];
        if (thisChannel.visible = true) {
            var theHisto = thisChannel.histogram;
            // 0 or black
            if (theHisto[0] == theTotal) {
                thisChannel.visible = false;
                thisChannel.remove();
            } else {
                thisChannel.visible = true;
            }
        }
    }
    app.preferences.rulerUnits = originalRulerUnits;
}

[alinaj84027284]

Thank you so much!
This is just what is needed.

Is it possible to make the script work not on all the alpha channels, but only on the selected one?

[Stephen_A_Marsh]

The following code simply removes selected channels, whether they are black or white:

// Remove selected channels
// based on code from c.pfaffenbichler
if (app.documents.length > 0) {
    var doc = activeDocument;
    var chanArray = doc.activeChannels;
    for (var i = 0; i < chanArray.length; i++) {
        chanArray[i].remove();
    }
}

[c.pfaffenbichler]

// 2022, use it at your own risk;
if (app.documents.length > 0) {
    var myDocument = app.activeDocument;
    var theChannels = myDocument.activeChannels;
    var originalRulerUnits = app.preferences.rulerUnits;
    app.preferences.rulerUnits = Units.PIXELS;
    var theTotal = Number(myDocument.width) * Number(myDocument.height);
    for (var m = theChannels.length - 1; m >= 0; m--) {
        var thisChannel = theChannels[m];
        if (thisChannel.visible = true) {
            var theHisto = thisChannel.histogram;
            // 255 or black
            if (theHisto[255] == theTotal) {
                thisChannel.visible = false;
                thisChannel.remove();
            } else {
                thisChannel.visible = true;
            }
        }
    }
    app.preferences.rulerUnits = originalRulerUnits;
}

[Stephen_A_Marsh]

@c.pfaffenbichler – I think that is what @alinaj84027284 is looking for... I think that you forgot to change to:

// 0 or black
if (theHisto[0] == theTotal)

To only remove selected black channels while retaining selected white channels.

[c.pfaffenbichler]

Ah, sorry, not paying sufficient attention …