将真彩色图像变为256色灰度(BIG5码):

 

 

 

将RGB想成3D之X,Y,Z轴,则BMP的RGB为(r,g,b)与座标(Y,Y,Y)距离最小时的Y即为灰阶值

Y = 0.29900 * R + 0.58700 * G + 0.11400 * B

整数化

Y = ( 9798*R + 19235*G + 3735*B) / 32768

RGB(Y, Y, Y)就可以了

 

需一个内有彩色图的PictureBox, CommandBox

Option Explicit

Private Declare Function GetPixel Lib "gdi32" _

(ByVal hdc As Long, ByVal x As Long, ByVal Y As Long) As Long

Private Declare Function SetPixelV Lib "gdi32" _

(ByVal hdc As Long, ByVal x As Long, _

ByVal Y As Long, ByVal crColor As Long) As Long

Private tmpPic As Picture

 

Private Sub Form_Load()

Picture1.ScaleMode = 3 设为Pixel

Picture1.AutoRedraw = True 设定所有Pixel的改变不立即在pictureBox上显示

Set tmpPic = Picture1.Picture

End Sub

 

Private Sub Command1_click()

Dim width5 As Long, heigh5 As Long, rgb5 As Long

Dim hdc5 As Long, i As Long, j As Long

Dim bBlue As Long, bRed

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