Image Histogram

davek604

Hello

I'm trying to extract the max intensity value at each frame in a sequence. I could do a count and get the max intensity from the data table. However it seems that it would be easier and simpler code if I could get it from the image histograms. I've found the Histogram.AbsoluteRange command in the help files which seems like it would be ideal. I'm using the following code

	Dim test
        Dim im As McImage
        im = ThisApplication.ActiveImage
        test(1,im) = im.Histogram.AbsoluteRange

I get an error about the object variable being empty, but as far as I can tell im has a value and as its a single channel image I've tried 0 and 1 for the channel but neither works. I can't see where the mistake is, any help appreciated

Regards

David

YuriG

Hi David,

You have to activate ProcessActiveFrameOnly to get histogram data of active frame. AbsoluteRange retuns a 2D array of Start/End values per channel.

    Public Sub PrintHistStats
        Dim im As McImage=ThisApplication.ActiveImage
        If im Is Nothing Then Exit Sub
        Dim hist As MediaCy.IQL.Operations.McHistogram=im.Histogram
        'measure only active frame
        hist.Mode=MediaCy.IQL.Operations.mcHistogramMode.mchmProcessActiveFrameOnly
        ThisApplication.Output.Show
        ThisApplication.Output.Clear
        For i As Integer=0 To im.FrameCount-1
            im.ActiveFrameIndex=i
            Dim mean As Object=hist.Mean
            Dim absRange As Object=hist.AbsoluteRange
            ThisApplication.Output.PrintMessage(String.Format("Frame = {0}, Mean ={1}, AbsoluteRange = {2}",i+1,ThisApplication.GlobalTools.McToText(mean).Value,ThisApplication.GlobalTools.McToText(absRange,New Object(){"","",":",";"}).Value))
        Next
    End Sub

You can find more info in the help on IMcHistogram page and the methods.

Image-Pro Premier Automation Help AbsoluteRange Property (Channel, SourceImage) Automation Reference ► MediaCy.IQL.Operations ► IMcHistogram ► AbsoluteRange[([( Int32, Object])]) Visual Basic

Returns the absolute minimum and maximum luminanance.

Declaration Syntax

Visual Basic

ReadOnly Property AbsoluteRange ( _
	Channel As Integer, _
	SourceImage As Object _
) As Object
	Get

Parameters

Channel (Int32)

SourceImage (Object)

Remarks

These are not the same as McImage.RangeMin and McImage.RangeMax which are set by the user for floating point images, and represent the minimum and maximum possible values for integral image types. The values may also differ from the Min and Max McHistogram properties. The Min and Max properties give the BinXValues element of the lowest and highest, respectively, bins with non-zero counts. These values will usually differ from the AbsoluteRange for floating point image types and where the BinCount is less than MaxBinCount. AbsoluteRange is exposed as a 2D array ([IMcIMage.NumberOfChannels][2] in C, (0 to 1,0 to IMcIMage.NumberOfChannels-1) in VB) if Channel=-1, or an array containing two double precision floating point values if Channel is non-negative. If the source McImage.ActiveFrameRange specifies some frames, then unless the Mode mchmProcessActiveFrameOnly bit is set or the SampledFrame property is non-negative, the AbsoluteRange is computed from all of the specified frames. If the Mode mchmProcessActiveFrameOnly bit is set, then only the McImage.ActiveFrame is conisidered. If the Mode mchmIgnoreAoi bit is set, then any Aoi is ignored. The AbsoluteRange property honors the Interpretation property and also the Mode mchmApplyIntensityCalibration flag. If the Interpretation is one that has a natural luminance channel (e.g., mciHSL or mciHSI), then when the Mode mchmApplyIntensityCalibration flag is set, intensity calibration is only applied to the luminance channel.

Regards,

Yuri
 

davek604

Hello Yuri

That works

Thanks

David