image processing question

[celtics]

Image Gray Scale Question
my B&W image has gray scale problem. it looks good for most part.
how to improve it?. How to (modify)Or(add to)) this header to improve gray scale?. MFC/SDI.
Celtics

LPBITMAPINFO PbmiHeader = (LPBITMAPINFO)new BYTE[sizeof(BITMAPINFOHEADER) + 256 * sizeof(RGBQUAD)];
PbmiHeader->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
PbmiHeader->bmiHeader.biWidth = Width;
PbmiHeader->bmiHeader.biHeight = Height;
PbmiHeader->bmiHeader.biPlanes = 1;
PbmiHeader->bmiHeader.biBitCount = 8;
PbmiHeader->bmiHeader.biCompression = 0;
PbmiHeader->bmiHeader.biSizeImage = 0;
PbmiHeader->bmiHeader.biXPelsPerMeter = 0;
PbmiHeader->bmiHeader.biYPelsPerMeter = 0;
PbmiHeader->bmiHeader.biClrUsed = 0;
PbmiHeader->bmiHeader.biClrImportant = 0;
for(int i=0; i<256; i++) {
PbmiHeader->bmiColors[i].rgbBlue = i;
PbmiHeader->bmiColors[i].rgbGreen = i;
PbmiHeader->bmiColors[i].rgbRed = i;
PbmiHeader->bmiColors[i].rgbReserved = 0;
}
HDC hdc = pDC->GetSafeHdc();
StretchDIBits( hdc, 0, 0,
Width1,
Height1,
0, 0,
Width,
Height,
data,
PbmiHeader,
DIB_RGB_COLORS,
SRCCOPY );

[Marc G]

What do you mean with "improve"? Adjust contrast, brightness, gamma? Something else?

[celtics]

my B&W image has gray scale problem. it looks good for most part.
needs to be smoothed uniformaly. Dark areas need to be dark uniformaly without
any fuzziness or impurities of other colors. I do not know the image processing
terms for it.(maybe gamma is the proper term for it).
How to (modify)Or(add to)) this header to improve contrast,gamma?. MFC/SDI.
Celtics

LPBITMAPINFO PbmiHeader = (LPBITMAPINFO)new BYTE[sizeof(BITMAPINFOHEADER) + 256 * sizeof(RGBQUAD)];
PbmiHeader->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
PbmiHeader->bmiHeader.biWidth = Width;
PbmiHeader->bmiHeader.biHeight = Height;
PbmiHeader->bmiHeader.biPlanes = 1;
PbmiHeader->bmiHeader.biBitCount = 8;
PbmiHeader->bmiHeader.biCompression = 0;
PbmiHeader->bmiHeader.biSizeImage = 0;
PbmiHeader->bmiHeader.biXPelsPerMeter = 0;
PbmiHeader->bmiHeader.biYPelsPerMeter = 0;
PbmiHeader->bmiHeader.biClrUsed = 0;
PbmiHeader->bmiHeader.biClrImportant = 0;
for(int i=0; i<256; i++) {
PbmiHeader->bmiColors[i].rgbBlue = i;
PbmiHeader->bmiColors[i].rgbGreen = i;
PbmiHeader->bmiColors[i].rgbRed = i;
PbmiHeader->bmiColors[i].rgbReserved = 0;
}
HDC hdc = pDC->GetSafeHdc();
StretchDIBits( hdc, 0, 0,
Width1,
Height1,
0, 0,
Width,
Height,
data,
PbmiHeader,
DIB_RGB_COLORS,
SRCCOPY );

[Marc G]

What you want to do cannot be done by simply adding something to the header. You'll have to write your own image filter functions to apply a gaussion smooth filter and perhaps to remove noise.

For implementing image filters, take a look at http://www.codeguru.com/bitmap/index.shtml for example http://www.codeguru.com/bitmap/BlurBlendMethod.html

[yiannakop]

It looks like you need some kind of local histogram equalization. This mean that u have to work with small blocks of the image and equalize the histogram of each block.