Retriving different histograms from activeDocument

I do not know javascript or photoshop scripting I only hack at code i steal from script I download. In the Photoshop CS5 Java scripting there seems to be a sample script names Histogram.jsx it get all four channels I never understood what Adobe fifth Colors was about. it looks like this

// Function to activate all the channels according to the documents mode // Takes a document reference for input function TurnOnDocumentHistogramChannels(inDocument) {     // see how many channels we need to activate     var visibleChannelCount = 0     // based on the mode of the document     switch (inDocument.mode) {         case DocumentMode.BITMAP:         case DocumentMode.GRAYSCALE:         case DocumentMode.INDEXEDCOLOR:             visibleChannelCount = 1             break;         case DocumentMode.DUOTONE:             visibleChannelCount = 2             break;         case DocumentMode.RGB:         case DocumentMode.LAB:             visibleChannelCount = 3             break;         case DocumentMode.CMYK:             visibleChannelCount = 4             break;         case DocumentMode.MULTICHANNEL:             default:             visibleChannelCount = inDocument.channels.length + 1             break;     }     // now get the channels to activate into a local array     var aChannelArray = new Array()     // index for the active channels array     var aChannelIndex = 0     for(var channelIndex = 0; channelIndex < inDocument.channels.length;             channelIndex++) {         if (channelIndex < visibleChannelCount) {             aChannelArray[aChannelIndex++] = inDocument.channels[channelIndex]         }     }     // now activate them     inDocument.activeChannels = aChannelArray } // Save the current preferences var startRulerUnits = app.preferences.rulerUnits var startTypeUnits = app.preferences.typeUnits var startDisplayDialogs = app.displayDialogs // Set Adobe Photoshop CS5 to use pixels and display no dialogs app.preferences.rulerUnits = Units.PIXELS app.preferences.typeUnits = TypeUnits.PIXELS app.displayDialogs = DialogModes.NO // if there are no documents open then try to open a sample file if (app.documents.length == 0) {     open(File(app.path + "/Samples/Fish.psd")) } // get a reference to the working document var docRef = app.activeDocument // create the output file // first figure out which kind of line feeds we need if ($.os.search(/windows/i) != -1) {     fileLineFeed = "Windows" } else {     fileLineFeed = "Macintosh" } // create the output file accordingly fileOut = new File("~/Desktop/Histogram.log") fileOut.lineFeed = fileLineFeed fileOut.open("w", "TEXT", "????") // write out a header fileOut.write("Histogram report for " + docRef.name) // find out how many pixels I have var totalCount = docRef.width.value * docRef.height.value // more info to the out file fileOut.write(" with a total pixel count of " + totalCount + "\n") // channel indexer var channelIndex = 0 // remember which channels are currently active var myActiveChannels = app.activeDocument.activeChannels // document histogram only works in these modes if (docRef.mode == DocumentMode.RGB ||     docRef.mode == DocumentMode.INDEXEDCOLOR ||     docRef.mode == DocumentMode.CMYK) {     // activate the main channels so we can get the documents histogram     TurnOnDocumentHistogramChannels(docRef)     // Output the documents histogram     OutputHistogram(docRef.histogram, "Luminosity", fileOut) } // local reference to work from var myChannels = docRef.channels // loop through each channel and output the histogram for (var channelIndex = 0; channelIndex < myChannels.length; channelIndex++) {     // the channel has to be visible to get a histogram     myChannels[channelIndex].visible= true     // turn off all the other channels     for (var secondaryIndex = 0; secondaryIndex < myChannels.length;             secondaryIndex++) {         if (channelIndex != secondaryIndex) {             myChannels[secondaryIndex].visible= false         }     } // Use the function to dump the histogram OutputHistogram(myChannels[channelIndex].histogram,     myChannels[channelIndex].name, fileOut) } // close down the output file fileOut.close() alert("Histogram file saved to: " + fileOut.fsName) // reset the active channels docRef.activeChannels = myActiveChannels // Reset the application preferences app.preferences.rulerUnits = startRulerUnits app.preferences.typeUnits = startTypeUnits app.displayDialogs = startDisplayDialogs // Utility function that takes a histogram and name // and dumps to the output file function OutputHistogram(inHistogram, inHistogramName, inOutFile) {     // find ouch which count has the largest number     // I scale everything to this number for the output     var largestCount = 0     // a simple indexer I can reuse     var histogramIndex = 0     // see how many samples we have total     var histogramCount = 0     // search through all and find the largest single item     for (histogramIndex = 0; histogramIndex < inHistogram.length;             histogramIndex++) {         histogramCount += inHistogram[histogramIndex]         if (inHistogram[histogramIndex] > largestCount)             largestCount = inHistogram[histogramIndex]     }     // These should match     if (histogramCount != totalCount) {         alert("Something bad is happening!")     }     // see how much each "X" is going to count as     var pixelsPerX = largestCount / 100     // output this data to the file     inOutFile.write("One X = " + pixelsPerX + " pixels.\n")     // output the name of this histogram     inOutFile.write(inHistogramName + "\n")     // loop through all the items and output in the following format     // 001     // 002     for (histogramIndex = 0; histogramIndex < inHistogram.length;             histogramIndex++) {     // I need an extra "0" for this line item to keep everything in line     if (histogramIndex < 10)         inOutFile.write("0")     // I need an extra "0" for this line item to keep everything in line     if (histogramIndex < 100)         inOutFile.write("0")     // output the index to file     inOutFile.write(histogramIndex)     // some spacing to make it look nice     inOutFile.write(" ")     // figure out how many X’s I need     var outputX = inHistogram[histogramIndex] / largestCount * 100     // output the X’s     for (var a = 0; a < outputX; a++)         inOutFile.write("X")     inOutFile.write("\n")     }     inOutFile.write("\n") }