GDI Plus Image Histogram

[Jardz]

Hi all,

I'm trying to better understand the excellent GDIP UDF by Authenticity

So I set myself a simple project to try and create a tonal histogram of an image; I use this in Photoshop a lot.

I started with an old example by Toady at the below link (Thank you Toady for getting me started)

Unfortunately 'PixelGetColor' seems very slow, so I wanted to see how fast GdipGetPixel would be.

So, starting with Toady's example, and using GdipGetPixel function by Vossen and ImageScale and Greyscale functions by Uez (Thank you to all) I have the script below...

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#include <GDIP.au3>
#include <Array.au3>
#include <GUIConstants.au3>


Global $iSampleRate = 20000 ; Number of pixels read for histogram, the higher the more accurate but slower.
Global $histos, $histo

$gui = GUICreate("Histogram",278,200,-1,-1)
$pen = GuiCtrlCreateGraphic(10,10, 258, 150)
GUICtrlSetBkColor(-1,0xFFFFFF)

GUICtrlCreateLabel("Sample Rate:",20,160)
$sample = GUICtrlCreateInput($iSampleRate,20,175,70,20)

;GUICtrlSetState(-1, $GUI_DISABLE)
$BtnOpen= GUICtrlCreateButton("Open", 180, 165, 78, 30)
GUISetState()

While 1
Switch GUIGetMsg()
Case $BtnOpen
_main()

Case $GUI_EVENT_CLOSE
_GDIPlus_ShutDown()
Exit

EndSwitch
WEnd

Func _main()
Local $tmp
$iSampleRate = GUICtrlRead($sample)
If $tmp < 1 and $tmp > 99999999 Then
GUICtrlSetData($sample,10000)
$iSampleRate = 10000
EndIf
Local $sFile = FileOpenDialog("Open File", @WorkingDir, "All Picture Files (*.bmp;*.gif;*.jpg;*.jpeg;*.tif;*.tiff;*.png)", 3)
Local $t = TimerInit()
$aArrayHist = _Histogram($sFile, $iSampleRate)
Local $d = Round(TimerDiff($t)/1000,2)
ConsoleWrite("Time to build histogram = " & $d & @CRLF)
RenderHistogram($aArrayHist)
Local $d = Round(TimerDiff($t)/1000,2)
ConsoleWrite("Total Time = " & $d & @CRLF)
EndFunc

Func RenderHistogram($a)
Local $max = _ArrayMax($a,1,1)
GuiCtrlDelete($pen)
$pen=GuiCtrlCreateGraphic(10,10, 258, 150)
GUICtrlSetBkColor(-1,0xFFFFFF)
GUICtrlSetState(-1, $GUI_DISABLE)
For $i = 1 To UBound($a)-1
GUICtrlSetGraphic($pen,$GUI_GR_MOVE, $i,150)
GUICtrlSetGraphic($pen,$GUI_GR_LINE, $i,150 - Round(140*($a[$i]/$max),0))
Next
GUICtrlSetColor(-1,0x000000)
EndFunc

Func _Histogram($fImage, $iSampleRate)
If $fImage = "" Then Return SetError(1, 0, 0)
If Not FileExists($fImage) Then Return SetError(2, 0, 0)

Local $fName = StringRegExpReplace($fImage, ".*\\(.*).{4}", "$1")
Local $declared = True
If Not $ghGDIPDll Then
_GDIPlus_Startup()
$declared = False
EndIf
Local $hImageFromFile = _GDIPlus_ImageLoadFromFile($fImage)
Local $iWidth = _GDIPlus_ImageGetWidth($hImageFromFile)
Local $iHeight = _GDIPlus_ImageGetHeight($hImageFromFile)

Local $ratio
If $iWidth*$iHeight > $iSampleRate Then
$ratio = $iWidth/$iHeight
$iW = Int(Sqrt($iSampleRate*$ratio))
$iH = Int(sqrt($iSampleRate/$ratio))
Else
$iW = $iWidth
$iH = $iHeight
EndIf

Local $hImageThumbnail = DllCall($ghGDIPDll, "uint", "GdipCreateBitmapFromScan0", "int", $iW, "int", $iH, "int", 0, "int", 0x0026200A, "ptr", 0, "int*", 0)
If @error Then Return SetError(3, 0, 0)
$hImageThumbnail = $hImageThumbnail[6]
Local $hBmpCtxt = _GDIPlus_ImageGetGraphicsContext($hImageThumbnail)
DllCall($ghGDIPDll, "uint", "GdipSetInterpolationMode", "handle", $hBmpCtxt, "int", 7)
_GDIPlus_GraphicsDrawImageRect($hBmpCtxt, $hImageFromFile, 0, 0, $iW, $iH)
_GDIPlus_ImageDispose($hImageFromFile)
_GDIPlus_GraphicsDispose($hBmpCtxt)

; If you don't want to transfer to greyscale then comment out below
;#CS
$hImageContext = _GDIPlus_ImageGetGraphicsContext($hImageThumbnail)
Local $tNegMatrix, $pNegMatrix
$tNegMatrix = _GDIPlus_ColorMatrixCreateGrayScale()
$pNegMatrix = DllStructGetPtr($tNegMatrix)
$hIA = _GDIPlus_ImageAttributesCreate()
_GDIPlus_ImageAttributesSetColorMatrix($hIA, 0, True, $pNegMatrix)
_GDIPlus_GraphicsDrawImageRectRectIA($hImageContext, $hImageThumbnail, 0, 0, $iW, $iH, 0, 0, $iW, $iH, $hIA)
_GDIPlus_ImageAttributesDispose($hIA)
_GDIPlus_GraphicsDispose($hImageContext)
;#CE

$aHist = _BuildHistogramArray($hImageThumbnail)
_GDIPlus_ImageDispose($hImageThumbnail)
_GDIPlus_Shutdown()
Return $aHist
EndFunc

Func _BuildHistogramArray($hBitmap)

Local $tArgb, $pArgb, $aRet, $blue, $red, $green, $w, $h
$tArgb = DllStructCreate("dword Argb")
$pArgb = DllStructGetPtr($tArgb)

Local $Hist[257]
For $i = 0 To UBound($Hist) - 1
$Hist[$i] = 0
Next

$w = _GDIPlus_ImageGetWidth($hBitmap)
$h = _GDIPlus_ImageGetHeight($hBitmap)
ConsoleWrite("Thumbnail W = " & $w & @CRLF & "Thumbnail H = " & $h & @CRLF)

;-------------Use the following if you've changed the bitmap thumbnail to greyscale otherwise comment out and use the next one----------
For $i = 1 To $h
For $j = 1 To $w
$aRet = DllCall($ghGDIPDll, "int", "GdipBitmapGetPixel", "hwnd", $hBitmap, "int", $j, "int", $i, "ptr", $pArgb)
$Hist[Dec(Hex(DllStructGetData($tArgb, "Argb"),2))+1] +=1
$Hist[0] += 1
Next
Next

;-------------If you're keeping bitmap as RGB and not Greyscale then use below to build Array for Histogram------------------------------
#cs
For $i = 1 To $h
For $j = 1 To $w
$aRet = DllCall($ghGDIPDll, "int", "GdipBitmapGetPixel", "hwnd", $hBitmap, "int", $j, "int", $i, "ptr", $pArgb)
$color_hex = "0x" & Hex(DllStructGetData($tArgb, "Argb") ,6)
$Hist[Round((BitAND($color_hex,255) + BitShift(BitAND($color_hex,65280),0x08) + BitShift(BitAND($color_hex,16711680),0x10))/3,0)+1] += 1
$Hist[0] += 1
Next
Next
#ce
$Hist[2] = ($Hist[1] + $Hist[3])/2
ConsoleWrite("Total Count = " & $Hist[0] & @CRLF)
Return $Hist

EndFunc

Func ScaleImage($hImage, $iScaleW, $iScaleH, $iInterpolationMode = 7) ;coded by UEZ 2012
Local $iWidth = _GDIPlus_ImageGetWidth($hImage) * $iScaleW
Local $iHeight = _GDIPlus_ImageGetHeight($hImage) * $iScaleH
Local $hBitmap = DllCall($ghGDIPDll, "uint", "GdipCreateBitmapFromScan0", "int", $iWidth, "int", $iHeight, "int", 0, "int", 0x0026200A, "ptr", 0, "int*", 0)
If @error Then Return SetError(3, 0, 0)
$hBitmap = $hBitmap[6]
Local $hBmpCtxt = _GDIPlus_ImageGetGraphicsContext($hBitmap)
DllCall($ghGDIPDll, "uint", "GdipSetInterpolationMode", "handle", $hBmpCtxt, "int", $iInterpolationMode)
_GDIPlus_GraphicsDrawImageRect($hBmpCtxt, $hImage, 0, 0, $iWidth, $iHeight)
_GDIPlus_ImageDispose($hImage)
_GDIPlus_GraphicsDispose($hBmpCtxt)
Return $hBitmap
EndFunc

However, the reason I'm posting in General Help and Support is I found two functions within GDIP v1.1 (Vista and above?) that may be exactly what I want.

two dllcalls instead of 2000

GdipBitmapGetHistogramSize and GdipBitmapGetHistogram

http://msdn.microsoft.com/en-us/library/windows/desktop/ms536307(v=vs.85).aspx

I know nothing about dllcalls but I've tried altering various examples in GDIP.au3 to see if I can get these to work.

After hours of trying on the 'GdipBitmapGetHistogramSize' I've realized I have no hope without a better understanding; I keep getting '0' as a result.

I would greatly appreciate anyone who comes across this post with the knowledge and time to show me how to call these functions.

Many thanks

Jardz

[UEZ]

Do you mean something like that here?

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#include <GDIPlus.au3>

Global Enum $HistogramFormatARGB = 0, $HistogramFormatPARGB, $HistogramFormatRGB, $HistogramFormatGray, _
                            $HistogramFormatB, $HistogramFormatG, $HistogramFormatR, $HistogramFormatA

;http://msdn.microsoft.com/en-us/library/windows/desktop/ms534136(v=vs.85).aspx
Global Const $ImageFlagsNone = 0
Global Const $ImageFlagsScalable = 0x0001
Global Const $ImageFlagsHasAlpha = 0x0002
Global Const $ImageFlagsHasTranslucent  = 0x0004
Global Const $ImageFlagsPartiallyScalable = 0x0008
Global Const $ImageFlagsColorSpaceRGB = 0x0010
Global Const $ImageFlagsColorSpaceCMYK = 0x0020
Global Const $ImageFlagsColorSpaceGRAY = 0x0040
Global Const $ImageFlagsColorSpaceYCBCR = 0x0080
Global Const $ImageFlagsColorSpaceYCCK = 0x0100
Global Const $ImageFlagsHasRealDPI = 0x1000
Global Const $ImageFlagsHasRealPixelSize = 0x2000
Global Const $ImageFlagsReadOnly = 0x00010000
Global Const $ImageFlagsCaching = 0x00020000

Global $file = FileOpenDialog("Select Image", "", "Images (*.jpg;*.png;*.bmp;*.gif)")
If @error Then Exit
_GDIPlus_Startup()
Global $hBitmap = _GDIPlus_BitmapCreateFromFile($file)

Global $iHistogramFormat = $HistogramFormatRGB, $bAlpha = False

Global $aRes = DllCall($ghGDIPDll, "int", "GdipGetImageFlags", "handle", $hBitmap, "uint*", 0)
If BitAND($aRes[2], $ImageFlagsHasAlpha) Then
        $iHistogramFormat = $HistogramFormatARGB
        $bAlpha = True
EndIf
Global Const $iGetHistogramSize = _GDIPlus_BitmapGetHistogramSize($iHistogramFormat)

Global $tStructChannel0 = DllStructCreate("uint channel0[" & $iGetHistogramSize & "]")
Global $pStructChannel0 = DllStructGetPtr($tStructChannel0)
Global $tStructChannel1 = DllStructCreate("uint channel1[" & $iGetHistogramSize & "]")
Global $pStructChannel1 = DllStructGetPtr($tStructChannel1)
Global $tStructChannel2 = DllStructCreate("uint channel2[" & $iGetHistogramSize & "]")
Global $pStructChannel2 = DllStructGetPtr($tStructChannel2)
Global $tStructChannel3 = DllStructCreate("uint channel3[" & $iGetHistogramSize & "]")
Global $pStructChannel3 = 0
If $bAlpha Then $pStructChannel3 = DllStructGetPtr($tStructChannel3)


$r = _GDIPlus_BitmapGetHistogram($hBitmap, $iHistogramFormat, $iGetHistogramSize, $pStructChannel0, $pStructChannel1, $pStructChannel2, $pStructChannel3)


Global $a = 0, $r, $g, $b

For $i = 1 To $iGetHistogramSize
    If $bAlpha Then
        $a = DllStructGetData($tStructChannel0, "channel0", $i)
        $r = DllStructGetData($tStructChannel1, "channel1", $i)
        $g = DllStructGetData($tStructChannel2, "channel2", $i)
        $b = DllStructGetData($tStructChannel3, "channel3", $i)
    Else
        $r = DllStructGetData($tStructChannel0, "channel0", $i)
        $g = DllStructGetData($tStructChannel1, "channel1", $i)
        $b = DllStructGetData($tStructChannel2, "channel2", $i)
    EndIf
    ConsoleWrite("Alpha: " & @TAB & $a & @TAB & "R: " & $r & @TAB & @TAB & "G: " & $g & @TAB & @TAB & "B: " & $B & @LF)
Next


_GDIPlus_BitmapDispose($hBitmap)
_GDIPlus_Shutdown()

Exit
;http://msdn.microsoft.com/en-us/library/windows/desktop/ms536307(v=vs.85).aspx
Func _GDIPlus_BitmapGetHistogram($hBitmap, $iFormat, $iGetHistogramSize, $pStructChannel0, $pStructChannel1, $pStructChannel2, $pStructChannel3)
    Local $aRes =  DllCall($ghGDIPDll, "bool", "GdipBitmapGetHistogram", "handle", $hBitmap, "uint", $iFormat, "uint",  $iGetHistogramSize, "struct*", $pStructChannel0,  "struct*", $pStructChannel1,  "struct*", $pStructChannel2, "struct*", $pStructChannel3)
    If @error Then Return SetError(1, @error, 0)
    Return 1
EndFunc

;http://msdn.microsoft.com/en-us/library/windows/desktop/ms536308(v=vs.85).aspx
Func _GDIPlus_BitmapGetHistogramSize($iFormat)
    Local $aRes = DllCall($ghGDIPDll, "int", "GdipBitmapGetHistogramSize", "uint", $iFormat, "dword*", 0)
    If @error Then Return SetError(1, @error, 0)
    Return $aRes[2]
EndFunc

For an example have a look here: http://www.autoitscript.com/forum/index.php?showtopic=147777

Br,

UEZ

Edited February 10, 2013 by UEZ

[Jardz]

That's Genius! Thank you very much UEZ.

Looking at how you've done this I realise my own efforts were nowhere close and never going to work .

I have a lot to learn...

Again, thank you!