【已解决】获取灰度图rgb颜色分量不正确，恳求指教

xiehuahere

图片：


代码：

#include <GDIPlus.au3>

;Load image
Local $imgFile = FileOpenDialog("Choose Picture", @ScriptDir, "Pictures (*.jpg)", 1)
If @error Then Exit
ConsoleWrite("Image file: " & $imgFile & @CRLF)

_GDIPlus_Startup()
Local $hImage = _GDIPlus_ImageLoadFromFile($imgFile)
Local $iWidth = _GDIPlus_ImageGetWidth($hImage)
Local $iHeight = _GDIPlus_ImageGetHeight($hImage)
_GDIPlus_ImageDispose($hImage)
ConsoleWrite("Resolution: " & $iWidth & "x" & $iHeight & @CRLF)

Local $hBitmap = _GDIPlus_BitmapCreateFromFile($imgFile)
Local $tBitmapData = _GDIPlus_BitmapLockBits($hBitmap, 0, 0, $iWidth, $iHeight, $GDIP_ILMREAD, $GDIP_PXF32RGB)
Local $grayValue1 = get_luma_jpg($hBitmap, 279, 3)
Local $grayValue2 = get_luma_jpg($hBitmap, 279, 5)
ConsoleWrite("$grayValue1: " & $grayValue1 & ", $grayValue2: " & $grayValue2 & @CRLF)
_GDIPlus_BitmapUnlockBits($hBitmap, $tBitmapData)
_GDIPlus_BitmapDispose($hBitmap)
_GDIPlus_Shutdown()

;~         Luma = 0.299 * Red + 0.587 * Green + 0.114 * Blue
Func get_luma_jpg($hBitmap, $iX, $iY)
        Local $rgb = _GDIPlus_BitmapGetPixel($hBitmap, $iX, $iY)
        Return (0.299 * $rgb[0] + 0.587 * $rgb[1] + 0.114 * $rgb[2])
EndFunc   ;==>get_luma_jpg

; http://www.autoitscript.com/forum/topic/97922-semi-solved-need-help-with-dllcall-gdi-function/
Func _GDIPlus_BitmapGetPixel($hBitmap, $iX, $iY)
        Local $str = "byte r;byte g;byte b"
        Local $color = DllStructCreate($str)
        DllCall($ghGDIPDll, "int", "GdipBitmapGetPixel", "hwnd", $hBitmap, "int", $iX, "int", $iY, 'ptr', DllStructGetPtr($color))
        If @error Then
                MsgBox(48 + 262144, 'GdipBitmapGetPixel', @error & ': ' & @extended)
                Return SetError(@error, @extended, 0)
        EndIf
        
        Local $r = DllStructGetData($color, 'r')
        Local $g = DllStructGetData($color, 'g')
        Local $b = DllStructGetData($color, 'b')
        ;RGB shall be of the same value for grayscale image
        ConsoleWrite('R: ' & $r & ', G: ' & $g & ', B: ' & $b & @CRLF)
        
        Local $retValues[3] = [$r, $g, $b]
        Return $retValues
EndFunc   ;==>_GDIPlus_BitmapGetPixel

求解两点问题：
1. 获取出来的RGB分量明显不对。灰度图的RGB分量应该都是相等的，用imageJ可以看出：
  

2. _GDIPlus_BitmapLockBits 的作用是什么？网上搜索了还是没怎么明白。MSDN上没看到详细解释啊。

恳求图像处理方面的大神出手相救！

seniors

1、获取颜色不成功的原因是用_GDIPlus_BitmapLockBits锁定了，另获取颜色在UDF中本来就有，不需要自己写。
2、_GDIPlus_BitmapLockBits我也不清楚，应该是锁定图像数据到内存，这时可能不能用_GDIPlus_BitmapGetPixel颜色。
因为这时图像的数据已经返回在 $tagGDIPBITMAPDATA 结构，要读取数据要对$tagGDIPBITMAPDATA才有效。

#include <GDIPlus.au3>

;Load image
Local $imgFile = FileOpenDialog("Choose Picture", @ScriptDir, "Pictures (*.jpg)", 1)
If @error Then Exit
ConsoleWrite("Image file: " & $imgFile & @CRLF)

_GDIPlus_Startup()
Local $hBitmap = _GDIPlus_BitmapCreateFromFile($imgFile)
Local $iWidth = _GDIPlus_ImageGetWidth($hBitmap)
Local $iHeight = _GDIPlus_ImageGetHeight($hBitmap)
ConsoleWrite("Resolution: " & $iWidth & "x" & $iHeight & @CRLF)
;~ Local $tBitmapData = _GDIPlus_BitmapLockBits($hBitmap, 0, 0, $iWidth, $iHeight, $GDIP_ILMREAD, $GDIP_PXF24RGB)
Local $grayValue1 = get_luma_jpg($hBitmap, 309, 17)
Local $grayValue2 = get_luma_jpg($hBitmap, 279, 5)
ConsoleWrite("$grayValue1: " & $grayValue1 & ", $grayValue2: " & $grayValue2 & @CRLF)
;~ _GDIPlus_BitmapUnlockBits($hBitmap, $tBitmapData)
_GDIPlus_BitmapDispose($hBitmap)
_GDIPlus_Shutdown()

;~         Luma = 0.299 * Red + 0.587 * Green + 0.114 * Blue
Func get_luma_jpg($hBitmap, $iX, $iY)
        Local $rgb = _GDIPlus_BitmapGetPixel($hBitmap, $iX, $iY)
        $b = BitAND(0xFF, BitShift($rgb, 16))
        $g = BitAND(0xFF, BitShift($rgb, 8))
        $r = BitAND(0xFF, $rgb)
        ConsoleWrite($r & @TAB & $g & @TAB & $b & @CR)
        $ret = Int((30 * $r + $g * 59 + $b * 11) / 100)
        Return $ret
EndFunc   ;==>get_luma_jpg

xiehuahere

回复 2# seniors


试过的确可以了。
我用的Au3版本是3.3.7.15，低了点，_GDIPlus_BitmapGetPixel还没被收录到<GDIPlus.au3>里。我本地有个当时收录的<GDIPlusEx.au3>，里面倒是有这个函数。看来不追新就要落后了。

谢谢前辈指教！

lqs_lfzz

这个要学一下，获取颜色