Issue with creating bitmap image data for Format8bppIndexed and Format4bppIndexed

Question

We are using below method to convert byte array into bitmap . we have successfully converted 16,24,32 etc. Pixel formats but we are facing issue while converting 4 and 8 pixel
formats  image is rendering in blur format and image starting and ending positions are changed.
<summary>
/// Converting the raw data into bitmap
</summary>
<param name="buffer">Byte array of the image rawdata</param>
<param name="nWidth">Image width</param>
<param name="nHeight">Image height</param>
<param name="nBitCount">Image Pixel format</param>
<returns></returns>
internal
Bitmap ConvertRawDataToBitMap(byte[]
buffer, int nWidth,
int nHeight,
int nBitCount,PDIB
pDIB=null)
Size imageSize =
new
Size(nWidth, nHeight);
PixelFormat imagePixelFormat = GetPixelFormat(nBitCount);
Bitmap bitmap =
new
Bitmap(imageSize.Width, imageSize.Height, imagePixelFormat);
Rectangle wholeBitmap =
new
Rectangle(0, 0, bitmap.Width, bitmap.Height);
BitmapData bitmapData = bitmap.LockBits(wholeBitmap,
ImageLockMode.WriteOnly, imagePixelFormat);
//Marshal.Copy(buffer, 0, bitmapData.Scan0, buffer.Length);
Marshal.Copy(buffer, 0, bitmapData.Scan0, bitmapData.Stride * bitmap.Height);
bitmap.UnlockBits(bitmapData);
bitmap.RotateFlip(RotateFlipType.Rotate180FlipX);
return bitmap;
<summary>
/// Returns the pixel format from given bit count.
</summary>
<param name="nPixelBitCount">Pixel bit count example 4 or 8 or 16 or 24 ..etc</param>
<returns></returns>
private
PixelFormat GetPixelFormat(int
nPixelBitCount)
PixelFormat pixelFormat =
PixelFormat.Undefined;
switch (nPixelBitCount)
case 4:
pixelFormat =
PixelFormat.Format4bppIndexed;
break;
case 8:
pixelFormat =
PixelFormat.Format8bppIndexed;
break;
case 16:
pixelFormat =
PixelFormat.Format16bppRgb555;
break;
case 24:
pixelFormat =
PixelFormat.Format24bppRgb;
break;
case 32:
pixelFormat =
PixelFormat.Format32bppRgb;
break;
case 48:
pixelFormat =
PixelFormat.Format48bppRgb;
break;
case 64:
pixelFormat =
PixelFormat.Format64bppArgb;
break;
default:
pixelFormat =
PixelFormat.Undefined;
break;
return pixelFormat;
below is the converted image for 8 pixelformat
below is the Actual image
Please help me to find the solution.
Thanks in Advance,
 Madhava Reddy and Madhu

Answer 1

Hi ,
We got below errors in the screen shots inserted.
MemoryStream msEVPict1 = new MemoryStream(buffer);
EVPict.pDIB.ImageBitmap = new Bitmap(msEVPict1);
 MemoryStream
ms1 = new
MemoryStream(buffer);
System.Drawing.Image
img = Image
.FromStream(ms1);
Thanks,
Madhu & Madhav