vb2005中图像的对比度 [英] contrast of an image in vb2005

问题描述

有效调整C＃中图像的对比度

上述问题的解决方案在vb 2005中无效

solution for above question is not working in vb 2005

我需要vb2005中的解决方案

i need solution in vb2005

这是下面的c＃代码

public static Bitmap AdjustContrast（Bitmap Image，float Value）

public static Bitmap AdjustContrast(Bitmap Image, float Value)

{

Value = (100.0f + Value) / 100.0f;
Value *= Value;
Bitmap NewBitmap = (Bitmap)Image.Clone();
BitmapData data = NewBitmap.LockBits(
    new Rectangle(0, 0, NewBitmap.Width, NewBitmap.Height), 
    ImageLockMode.ReadWrite,
    NewBitmap.PixelFormat);

unsafe
{
    for (int y = 0; y < NewBitmap.Height; ++y)
    {
        byte* row = (byte*)data.Scan0 + (y * data.Stride);
        int columnOffset = 0;
        for (int x = 0; x < NewBitmap.Width; ++x)
        {
            byte B = row[columnOffset];
            byte G = row[columnOffset + 1];
            byte R = row[columnOffset + 2];

            float Red = R / 255.0f;
            float Green = G / 255.0f;
            float Blue = B / 255.0f;
            Red = (((Red - 0.5f) * Value) + 0.5f) * 255.0f;
            Green = (((Green - 0.5f) * Value) + 0.5f) * 255.0f;
            Blue = (((Blue - 0.5f) * Value) + 0.5f) * 255.0f;

            int iR = (int)Red;
            iR = iR > 255 ? 255 : iR;
            iR = iR < 0 ? 0 : iR;
            int iG = (int)Green;
            iG = iG > 255 ? 255 : iG;
            iG = iG < 0 ? 0 : iG;
            int iB = (int)Blue;
            iB = iB > 255 ? 255 : iB;
            iB = iB < 0 ? 0 : iB;

            row[columnOffset] = (byte)iB;
            row[columnOffset + 1] = (byte)iG;
            row[columnOffset + 2] = (byte)iR;

            columnOffset += 4;
        }
    }
}

NewBitmap.UnlockBits(data);

return NewBitmap;

}

&这里是vb2005代码

& here is vb2005 code

公共共享函数AdjustContrast（图像为位图，值为单）作为位图

Public Shared Function AdjustContrast(Image As Bitmap, Value As Single) As Bitmap

Value = (100F + Value) / 100F
Value *= Value
Dim NewBitmap As Bitmap = DirectCast(Image.Clone(), Bitmap)

Dim data As BitmapData = NewBitmap.LockBits(New Rectangle(0, 0, NewBitmap.Width, NewBitmap.Height), ImageLockMode.ReadWrite, NewBitmap.PixelFormat)

For y As Integer = 0 To NewBitmap.Height - 1
    Dim row As Pointer(Of Byte) = CType(data.Scan0, Pointer(Of Byte)) + (y * data.Stride)
    Dim columnOffset As Integer = 0
    For x As Integer = 0 To NewBitmap.Width - 1
        Dim B As Byte = row(columnOffset)
        Dim G As Byte = row(columnOffset + 1)
        Dim R As Byte = row(columnOffset + 2)

        Dim Red As Single = R / 255F
        Dim Green As Single = G / 255F
        Dim Blue As Single = B / 255F
        Red = (((Red - 0.5F) * Value) + 0.5F) * 255F
        Green = (((Green - 0.5F) * Value) + 0.5F) * 255F
        Blue = (((Blue - 0.5F) * Value) + 0.5F) * 255F

        Dim iR As Integer = CInt(Red)
        iR = If(iR > 255, 255, iR)
        iR = If(iR < 0, 0, iR)
        Dim iG As Integer = CInt(Green)
        iG = If(iG > 255, 255, iG)
        iG = If(iG < 0, 0, iG)
        Dim iB As Integer = CInt(Blue)
        iB = If(iB > 255, 255, iB)
        iB = If(iB < 0, 0, iB)

        row(columnOffset) = CByte(iB)
        row(columnOffset + 1) = CByte(iG)
        row(columnOffset + 2) = CByte(iR)

        columnOffset += 4
    Next
Next

NewBitmap.UnlockBits(data)

Return NewBitmap

结束功能

Dim row As Pointer（Of Byte）= CType（data.Scan0，Pointer（Of Byte））+（y * data.Stride）

Dim row As Pointer(Of Byte) = CType(data.Scan0, Pointer(Of Byte)) + (y * data.Stride)

上面的行给出错误，因为vb不支持

above line gives error since vb does not support

Dim row As Pointer（Of Byte）

Dim row As Pointer(Of Byte)

推荐答案

这是我对转换的尝试。我正在使用 IntPtr 数据结构，用于处理保持未管理的指针并执行指针添加以获得每行的 IntPtr 。然后，当它通过该行时，我正在使用 Marshal.ReadByte 和 Marshal.WriteByte 方法来处理读取和写入非托管数据。我测试了它似乎工作。

Here's my attempt at the conversion. I'm using the IntPtr data structure to handle holding the unmanged pointer and to do the pointer addition to get an IntPtr for each row. Then as it goes through the row, I'm using the Marshal.ReadByte and Marshal.WriteByte methods to handle reading and writing the unmanaged data. I tested and it seems to work.

value = (100.0F + value) / 100.0F
    value *= value
    Dim NewBitmap As Bitmap = DirectCast(Image.Clone(), Bitmap)

    Dim data As BitmapData = NewBitmap.LockBits(New Rectangle(0, 0, NewBitmap.Width, NewBitmap.Height), ImageLockMode.ReadWrite, NewBitmap.PixelFormat)

    For y As Integer = 0 To NewBitmap.Height - 1

        Dim RowPtr = IntPtr.Add(data.Scan0, y * data.Stride)

        Dim columnOffset As Integer = 0
        For x As Integer = 0 To NewBitmap.Width - 1
            Dim B As Byte = System.Runtime.InteropServices.Marshal.ReadByte(RowPtr, columnOffset)
            Dim G As Byte = System.Runtime.InteropServices.Marshal.ReadByte(RowPtr, columnOffset + 1)
            Dim R As Byte = System.Runtime.InteropServices.Marshal.ReadByte(RowPtr, columnOffset + 2)

            Dim Red As Single = R / 255.0F
            Dim Green As Single = G / 255.0F
            Dim Blue As Single = B / 255.0F
            Red = (((Red - 0.5F) * value) + 0.5F) * 255.0F
            Green = (((Green - 0.5F) * value) + 0.5F) * 255.0F
            Blue = (((Blue - 0.5F) * value) + 0.5F) * 255.0F

            Dim iR As Integer = CInt(Red)
            iR = If(iR > 255, 255, iR)
            iR = If(iR < 0, 0, iR)
            Dim iG As Integer = CInt(Green)
            iG = If(iG > 255, 255, iG)
            iG = If(iG < 0, 0, iG)
            Dim iB As Integer = CInt(Blue)
            iB = If(iB > 255, 255, iB)
            iB = If(iB < 0, 0, iB)

            System.Runtime.InteropServices.Marshal.WriteByte(RowPtr, columnOffset, CByte(iB))
            System.Runtime.InteropServices.Marshal.WriteByte(RowPtr, columnOffset + 1, CByte(iG))
            System.Runtime.InteropServices.Marshal.WriteByte(RowPtr, columnOffset + 2, CByte(iR))

            columnOffset += 4
        Next

    Next

    NewBitmap.UnlockBits(data)

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