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Copy bitmap data to an 8bit grayscale windows bitmap
Rank: Member
Groups: Member
Joined: 1/5/2005(UTC)
Posts: 20
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I'm using scan0 to copy an Aurigma bitmap to a Windows Bitmap. When I use a 32bit ARGb bitmap it works just fine (piBitmapData->ConvertTo32bppArgb(255,TRUE,NULL);) But I need an 8 Bit grayscale Windows bitmap. When I convert to 8bit grayscale (piBitmapData->ConvertTo8bppGrayscale(FALSE,0,NULL);), it doesn't go into the bitmap correctly (it makes multiple small copies of itself). Here is how I create the windows bitmap: Code: piBitmapData->get_Height(&myHeight);
piBitmapData->get_Width(&myWidth);
piBitmapData->get_Scan0(&myScan0);
piBitmapData->get_BitsPerPixel(&myBitsPerPixel);
piBitmapData->get_Stride(&myStride);
piBitmapData->get_MemoryUsed(&myMemoryUsed);
CWnd* pWnd = CWnd::GetDesktopWindow();
CBitmap bitmap, bitmap2;
CWindowDC dc(pWnd);
CDC memDC;
CRect rect;
memDC.CreateCompatibleDC(&dc);
DWORD mydwCount;
mydwCount = (myHeight*myStride)-1;
bitmap.CreateBitmap(myWidth,myHeight,1,8,NULL);
bitmap.CreateCompatibleBitmap(&dc, myWidth,myHeight );// this works for 32 bit bitmaps
bitmap.SetBitmapBits(mydwCount,(void *)myScan0);
dc.SelectObject(&bitmap);
But I don't know how to tell windows to create an 8bit grayscale bitmap. If I try using the following, the bitmap comes out null: Code:bitmap.CreateBitmap(myWidth,myHeight,1,8,(void *)myScan0);
Any help would be greatly appreciated. Thanks, Ken Edited by user Sunday, December 23, 2007 6:14:41 PM(UTC)
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Rank: Advanced Member
Groups: Member, Administration
Joined: 8/2/2003(UTC)
Posts: 876
Thanks: 2 times
Was thanked: 27 time(s) in 27 post(s)
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Could you tell more detailed what you want to achieve? Meanwhile, several comments: - GDI does not support 8-bit grayscale bitmaps. However it supports 8-bit indexed bitmaps with grayscale palette.
- You try to create HBITMAP using CreateCompatibleBitmap from HDC which you receive from desktop. This way you will always have 32-bit image. That's why when you copy 8-bit grayscale pixels into such bitmap, it interprets it incorrectly.
- I am not familiar with MFC wrappers for GDI functions, but I would recommend to take a look at CreateDIBSection function (or its equivalent in MFC).
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Rank: Member
Groups: Member
Joined: 1/5/2005(UTC)
Posts: 20
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Thanks, I just resolved this this morning by creating a DIB (device independent bitmap), which gives full control over the pixel formats, instead of a DDB (device dependent bitmap). It works fine now.
Thanks again,
Ken
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Copy bitmap data to an 8bit grayscale windows bitmap
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