Iterating image lines pixel by pixel

[andyf65867865]

Could you show an example how to iterate image file lines pixel by pixel to detect is pixel line is completely "white" i.e. empty or not empty i.e. "not white".

So if line is full of white pixels then result is 0 if not then result is 1. Just for a sample.

The example is below. As you can observe, some lines are completely emty while othes is not. So how to iterate such an image in Photoshop script?

[Chuck Uebele]

You can try this:

#target photoshop
var doc = activeDocument
for(var i=0;i<doc.height;i++){
    doc.selection.deselect();
    getSelect (i, 0, i+1, doc.width)
    if(doc.histogram[255]==parseInt (doc.width)){
        checkSelet (i);
        if(doc.selection.bounds[2]<doc.width){$.writeln(false)}
        else{$.writeln(true)}
        }
    else{$.writeln(false)}
   }
function getSelect(top,left,bottom,right){
    var idsetd = charIDToTypeID( "setd" );
        var desc6 = new ActionDescriptor();
        var idnull = charIDToTypeID( "null" );
            var ref1 = new ActionReference();
            var idChnl = charIDToTypeID( "Chnl" );
            var idfsel = charIDToTypeID( "fsel" );
            ref1.putProperty( idChnl, idfsel );    
    desc6.putReference( idnull, ref1 );
    var idT = charIDToTypeID( "T   " );
        var desc7 = new ActionDescriptor();
        var idTop = charIDToTypeID( "Top " );
        var idPxl = charIDToTypeID( "#Pxl" );
        desc7.putUnitDouble( idTop, idPxl, top );
        var idLeft = charIDToTypeID( "Left" );
        var idPxl = charIDToTypeID( "#Pxl" );
        desc7.putUnitDouble( idLeft, idPxl, left );
        var idBtom = charIDToTypeID( "Btom" );
        var idPxl = charIDToTypeID( "#Pxl" );
        desc7.putUnitDouble( idBtom, idPxl, bottom );
        var idRght = charIDToTypeID( "Rght" );
        var idPxl = charIDToTypeID( "#Pxl" );
        desc7.putUnitDouble( idRght, idPxl, right );
    var idRctn = charIDToTypeID( "Rctn" );
    desc6.putObject( idT, idRctn, desc7 );
    executeAction( idsetd, desc6, DialogModes.NO );    
    }
function checkSelet(y){
        var idIntW = charIDToTypeID( "IntW" );
        var desc10 = new ActionDescriptor();
        var idnull = charIDToTypeID( "null" );
            var ref2 = new ActionReference();
            var idChnl = charIDToTypeID( "Chnl" );
            var idfsel = charIDToTypeID( "fsel" );
            ref2.putProperty( idChnl, idfsel );
        desc10.putReference( idnull, ref2 );
        var idT = charIDToTypeID( "T   " );
            var desc11 = new ActionDescriptor();
            var idHrzn = charIDToTypeID( "Hrzn" );
            var idPxl = charIDToTypeID( "#Pxl" );
            desc11.putUnitDouble( idHrzn, idPxl, 1 );
            var idVrtc = charIDToTypeID( "Vrtc" );
            var idPxl = charIDToTypeID( "#Pxl" );
            desc11.putUnitDouble( idVrtc, idPxl, y );
        var idPnt = charIDToTypeID( "Pnt " );
        desc10.putObject( idT, idPnt, desc11 );
        var idTlrn = charIDToTypeID( "Tlrn" );
        desc10.putInteger( idTlrn, 0 );
        var idAntA = charIDToTypeID( "AntA" );
        desc10.putBoolean( idAntA, true );
    executeAction( idIntW, desc10, DialogModes.NO );
    }

[andyf65867865]

where did u get it...

[Chuck Uebele]

I wrote it. Just a word of warning, It won't detect a full line that's transparent. Placing a colored layer under the layer you're checking would work better.

[andyf65867865]

I tried it with ps cs6 on 1 by 1 pixel document.
It only outputs false while pixel is white but if pixel is not white then there is an error

[Chuck Uebele]

I'll have to take a look later and see if my CS6 still works.

[SuperMerlin]

Just shortened your code Chuck and it does work now in CS6.

#target photoshop  
var doc = activeDocument       
for(var i=0;i<doc.height;i++){   
    getSelect (i, 0, i+1, doc.width);
    if(doc.histogram[255]==Number (doc.width))  $.writeln(true);
    else $.writeln(false);
}       
doc.selection.deselect(); 
function getSelect(top,left,bottom,right){  
var desc6 = new ActionDescriptor();  
var ref1 = new ActionReference();  
ref1.putProperty( charIDToTypeID('Chnl'), charIDToTypeID('fsel') );      
desc6.putReference( charIDToTypeID('null'), ref1 );  
var desc7 = new ActionDescriptor();  
desc7.putUnitDouble( charIDToTypeID('Top '), charIDToTypeID('#Pxl'), top );  
desc7.putUnitDouble( charIDToTypeID('Left'), charIDToTypeID('#Pxl'), left );  
desc7.putUnitDouble( charIDToTypeID('Btom'), charIDToTypeID('#Pxl'), bottom );  
desc7.putUnitDouble( charIDToTypeID('Rght'), charIDToTypeID('#Pxl'), right );  
desc6.putObject( charIDToTypeID('T   '), charIDToTypeID('Rctn'), desc7 );  
executeAction( charIDToTypeID('setd'), desc6, DialogModes.NO );     
};  

[Chuck Uebele]

Thanks. With PS 2017, it was registering transparent as white with the histogram. A full lime of transparent might throw that error.

[SuperMerlin]

Yes transparency does show as white in the histogram, it would take a lot more code to work out those lines.

[andyf65867865]

not sure is the code works properly...

for example, with the following sample picture (10 px height)

it outputs in javascript console

false

false

false

false

but for I understand it it should outputs next

false

false

true

false

true

false

false

true

false

false

because there are 10 lines in the picture and only three lines contains not white pixels

note that transparency does not matter here because source image will be flat

Am I describe the idea clear?

[SuperMerlin · Accepted solution]

Try this version...

#target photoshop;
app.bringToFront();
main();
function main(){
if(!documents.length) return;
try{
var doc = app.activeDocument;
app.displayDialogs = DialogModes.NO;
var strtRulerUnits = app.preferences.rulerUnits;
var strtTypeUnits = app.preferences.typeUnits;
app.preferences.rulerUnits = Units.PIXELS;
app.preferences.typeUnits = TypeUnits.PIXELS;
Left =0; Top = 0; Right = doc.width; Bottom =1;
var lineType=[];
for(var a = 0;a<doc.height; a++){
activeDocument.selection.select([[Left,Top],[Right,Top],[Right,Bottom],[Left,Bottom]], SelectionType.REPLACE, 0, false);
Top++; Bottom++;
var area = activeDocument.histogram;
if(area[255] != doc.width.value){
lineType.push(1);
}else{
lineType.push(0);
}}
activeDocument.selection.deselect();
var w = new Window("dialog","Lines",undefined, {closeButton: false});
w.dl = w.add("dropdownlist");
for(var z in lineType){w.dl.add("item", "Line " +(Number(z)+1) + " = " + lineType);}
w.dl.selection=0;
w.b = w.add("button",undefined,"Okay");
w.b.onClick = function(){w.close(0);}
w.show();
}catch(e){}
finally{
app.preferences.rulerUnits = strtRulerUnits;
app.preferences.typeUnits = strtTypeUnits;
}
};

[andyf65867865]

For some reason the code works too slow on real size A4 300 dpi documents... Maybe there is other fast logic to complete the same process?

[SuperMerlin]

Sorry no there isn't.

Matlab might be the way to go though as Photoshop is not good at this sort of thing.

[c.pfaffenbichler]

Have you tried the RAW code?

[andyf65867865]

Yes, I have tried the RAW code. It works allmost identical if not longer and there were some troubles with finishing the process.

[c.pfaffenbichler]

Can you provide a file for testing?

[c.pfaffenbichler]

In my test with an 8bit RGB image (210mm x 297mm at 300ppi) Supermerlin’s Script took only about half the time the Raw one did (roughly 27sec and 54sec).

So the advantage I had noticed in previous testing was apparently owed to some intermediate image size …

[c.pfaffenbichler]

Using the data from a RAW duplicate might be faster especially for larger images.

// based on code by paul riggott;

// 2017, use it at your own risk;

#target photoshop

File.prototype.readByte = function() {

  return this.read(1).charCodeAt(0);

};

function convertByteToSignedByte(num){

     var dec = (num | (num % 256))-128

     return dec;

};

function convertByteToLum( num){

     var dec = Math.round((num/256)*100);

     return dec;

};

function main(){

if(!documents.length) return;

if(activeDocument.mode != DocumentMode.LAB) {

var theCopy = activeDocument.duplicate("theCopy", true);

    var desc3 = new ActionDescriptor();

    desc3.putClass( charIDToTypeID( "T   " ), charIDToTypeID( "LbCM" ) );

executeAction( charIDToTypeID( "CnvM" ), desc3, DialogModes.NO );

    }

var Name = decodeURI(app.activeDocument.name).replace(/\.[^\.]+$/, '');

try{

var Path = activeDocument.path;

}catch(e){var Path = '~/Desktop';}

var rawFile = new File(Path +"/"+Name +".raw");

saveAsRaw(rawFile);

var len = 0;

var W = activeDocument.width.as('px');

CountW=0;

CountH=0;

rawFile.encoding = 'BINARY';

rawFile.open('r');

var theArray = new Array;

//////////////////

var theCheck = true;

while(!rawFile.eof){

var theL = convertByteToLum(rawFile.readByte());

convertByteToSignedByte(rawFile.readByte());

convertByteToSignedByte(rawFile.readByte());

if (theL != 100) {theCheck = false}; 

     len++;

     if(len % W == 0){

         CountH++;

         CountW=0;

  theArray.push(theCheck);

var theCheck = true;

         }

  else{

    CountW++;

     }

};

rawFile.close();

rawFile.remove();

try {theCopy.close(SaveOptions.DONOTSAVECHANGES)}

catch (e) {};

alert ("line white\n"+theArray.join("\n"))

};

//var time1 = Number(timeString());

main();

//var time2 = Number(timeString());

//alert("time: "+((time2-time1)/1000)+" seconds\nstart "+time1+"\nend "+time2);

function saveAsRaw(file) {

var desc1 = new ActionDescriptor();

var desc2 = new ActionDescriptor();

desc2.putString( charIDToTypeID('FlCr'), "8BIM" );

desc2.putBoolean( charIDToTypeID('ChnI'), true );

desc1.putObject( charIDToTypeID('As  '), charIDToTypeID('Rw  '), desc2 );

desc1.putPath( charIDToTypeID('In  '), new File( file ) );

desc1.putBoolean( charIDToTypeID('Cpy '), true );

executeAction( charIDToTypeID('save'), desc1, DialogModes.NO );

};

////// function to get the date //////

function timeString () {

  var now = new Date();

  return now.getTime()

  };