Image saved from Fingerprint sensor seems corrupted - windows

Question

I have been trying to put together code to actually save image from fingerprint sensors. I have already tried forums and this is my current code which saves file with correct file size but When i open the image, Its not image of fingerprint rather it looks like a corrupted image. Here is what it looks like.
My code is given below. Any help will be appreciated. I am new to windows development.
bool SaveBMP(BYTE* Buffer, int width, int height, long paddedsize, LPCTSTR bmpfile)
{
BITMAPFILEHEADER bmfh;
BITMAPINFOHEADER info;
memset(&bmfh, 0, sizeof(BITMAPFILEHEADER));
memset(&info, 0, sizeof(BITMAPINFOHEADER));
//Next we fill the file header with data:
bmfh.bfType = 0x4d42; // 0x4d42 = 'BM'
bmfh.bfReserved1 = 0;
bmfh.bfReserved2 = 0;
bmfh.bfSize = sizeof(BITMAPFILEHEADER) +
sizeof(BITMAPINFOHEADER) + paddedsize;
bmfh.bfOffBits = 0x36;
//and the info header:
info.biSize = sizeof(BITMAPINFOHEADER);
info.biWidth = width;
info.biHeight = height;
info.biPlanes = 1;
info.biBitCount = 8;
info.biCompression = BI_RGB;
info.biSizeImage = 0;
info.biXPelsPerMeter = 0x0ec4;
info.biYPelsPerMeter = 0x0ec4;
info.biClrUsed = 0;
info.biClrImportant = 0;
HANDLE file = CreateFile(bmpfile, GENERIC_WRITE, FILE_SHARE_READ,
NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
//Now we write the file header and info header:
unsigned long bwritten;
if (WriteFile(file, &bmfh, sizeof(BITMAPFILEHEADER),
&bwritten, NULL) == false)
{
CloseHandle(file);
return false;
}
if (WriteFile(file, &info, sizeof(BITMAPINFOHEADER),
&bwritten, NULL) == false)
{
CloseHandle(file);
return false;
}
//and finally the image data:
if (WriteFile(file, Buffer, paddedsize, &bwritten, NULL) == false)
{
CloseHandle(file);
return false;
}
//Now we can close our function with
CloseHandle(file);
return true;
}
HRESULT CaptureSample()
{
HRESULT hr = S_OK;
WINBIO_SESSION_HANDLE sessionHandle = NULL;
WINBIO_UNIT_ID unitId = 0;
WINBIO_REJECT_DETAIL rejectDetail = 0;
PWINBIO_BIR sample = NULL;
SIZE_T sampleSize = 0;
// Connect to the system pool.
hr = WinBioOpenSession(
WINBIO_TYPE_FINGERPRINT, // Service provider
WINBIO_POOL_SYSTEM, // Pool type
WINBIO_FLAG_RAW, // Access: Capture raw data
NULL, // Array of biometric unit IDs
0, // Count of biometric unit IDs
WINBIO_DB_DEFAULT, // Default database
&sessionHandle // [out] Session handle
);
// Capture a biometric sample.
wprintf_s(L"\n Calling WinBioCaptureSample - Swipe sensor...\n");
hr = WinBioCaptureSample(
sessionHandle,
WINBIO_NO_PURPOSE_AVAILABLE,
WINBIO_DATA_FLAG_RAW,
&unitId,
&sample,
&sampleSize,
&rejectDetail
);
wprintf_s(L"\n Swipe processed - Unit ID: %d\n", unitId);
wprintf_s(L"\n Captured %d bytes.\n", sampleSize);
PWINBIO_BIR_HEADER BirHeader = (PWINBIO_BIR_HEADER)(((PBYTE)sample) + sample->HeaderBlock.Offset);
PWINBIO_BDB_ANSI_381_HEADER AnsiBdbHeader = (PWINBIO_BDB_ANSI_381_HEADER)(((PBYTE)sample) + sample->StandardDataBlock.Offset);
PWINBIO_BDB_ANSI_381_RECORD AnsiBdbRecord = (PWINBIO_BDB_ANSI_381_RECORD)(((PBYTE)AnsiBdbHeader) + sizeof(WINBIO_BDB_ANSI_381_HEADER));
PBYTE firstPixel = (PBYTE)((PBYTE)AnsiBdbRecord) + sizeof(WINBIO_BDB_ANSI_381_RECORD);
SaveBMP(firstPixel, AnsiBdbRecord->HorizontalLineLength, AnsiBdbRecord->VerticalLineLength, AnsiBdbRecord->BlockLength, "D://test.bmp");
wprintf_s(L"\n Press any key to exit.");
_getch();
}

Answer 1

IInspectable is correct, the corruption looks like it's coming from your implicit use of color tables:
info.biBitCount = 8;
info.biCompression = BI_RGB;
If your data is actually just 24-bit RGB, you can do info.biBitCount = 24; to render a valid bitmap. If it's lower (or higher) than that, then you'll need to do some conversion work. You can check AnsiBdbHeader->PixelDepth to confirm that it's the 8 bits per pixel that you expect.
It also looks like your passing AnsiBdbRecord->BlockLength to SaveBMP isn't quite right. The docs for this field say:
WINBIO_BDB_ANSI_381_RECORD structure
BlockLength
Contains the number of bytes in this structure plus the number of bytes of sample image data.
So you'll want to make sure to subtract sizeof(WINBIO_BDB_ANSI_381_RECORD) before passing it as your bitmap buffer size.
Side note, make sure you free the memory involved after the capture.
WinBioFree(sample);
WinBioCloseSession(sessionHandle);