Image Histogram

MaurizioIEC

Hi,
I need to get the image histogram info (RGB image).
I tried this code

    '----------------------------------------------------------------------
    Dim hist As MediaCy.IQL.Operations.McHistogram = ImEmpty.Histogram
    Dim dMedia As Double = hist.Mean  <---- Error Type mismatch (10080)
    Dim dMinimo As Double = hist.Min<---- Error Type mismatch (10080)
    Dim dMassimo As Double  =hist.Max<---- Error Type mismatch (10080)
    Dim dStdDev As Double = hist.StdDev<---- Error Type mismatch (10080)
    Dim dModa As Double = hist.Mode<---- Error Type mismatch (10080)
    '----------------------------------------------------------------------
NOTE ImEmpty is a McImage instance
According to the IQL reference the Mean is a double parameter

In case of AOI presence on the image should I use the region access method ( some think similar at the follow code)? 
 
    Dim ra As McRegionAccess=ImEmpty.CreateRegionAccess()
    ra.RegionMask=ImEmpty.Aoi'process only active ROI

If yes which is the correct sintax to be used ? Thank you Maurizio

YuriG

Hi Maurizio,

If image is color, the Mean will be an array of values for every channel:

    Public Sub TestHist
        Dim hist As MediaCy.IQL.Operations.McHistogram = ThisApplication.ActiveImage.Histogram
        Dim dMedia As Double() = hist.Mean
        Debug.Print ThisApplication.GlobalTools.McToText(dMedia).Value
    End Sub

If you don't know what output type is, I recommend using Object : 

Public Sub TestHist2 Dim hist As MediaCy.IQL.Operations.McHistogram = ThisApplication.ActiveImage.Histogram Dim dMedia As Object = hist.Mean Debug.Print ThisApplication.GlobalTools.McToText(dMedia).Value End Sub
Regards,

Yuri

YuriG

Regarding ROI: histogram always uses ROI boundaries by default, so you don't have to do anything.

Yuri