TIFF and LibTiff Mail List Archive


2009.09.10 14:38 "[Tiff] 16-bit grayscale tiff to 8-bit grayscale in borland c++ (more info)", by Robert Zermeno
2009.09.11 01:43 "Re: [Tiff] 16-bit grayscale tiff to 8-bit grayscale in borland c++ (more info)", by Bob Friesenhahn
2009.09.11 00:37 "Re: [Tiff] 16-bit grayscale tiff to 8-bit grayscale in borland c++ (more info)", by Robert Zermeno

2009.09.10 14:38 "[Tiff] 16-bit grayscale tiff to 8-bit grayscale in borland c++ (more info)", by Robert Zermeno

I was not sure how to make a response to the user for everyone to see.  I had just posted my first message.  Do I just reply to the user that had emailed me to email her back and everyone else will receive my mail as well???  Oh, well, sorry for the additional post, but i want to make clear that I cannot use any other programs, plug-ins, or add-ons to perform the functionality.  I have to manually do it.  I understand the concept, but it just is not working and I want another persons opinion since the mail archieve has helped me out.

Again, here is the Tags of my file for
SubFileType (1 Long): Zero
ImageWidth (1 Long): 14592
ImageLength (1 Long): 6940
BitsPerSample (1 Short): 16
Compression (1 Short): Uncompressed
Photometric (1 Short): MinIsBlack
ImageDescription (13 ASCII): Space Imaging
StripOffsets (6940 Long): 56040, 85224, 114408, 143592, 172776,...
SamplesPerPixel (1 Short): 1
RowsPerStrip (1 Short): 1

StripByteCounts (6940 Long): 29184, 29184, 29184, 29184, 29184, 29184,...

MinSampleValue (1 Short): 0
MaxSampleValue (1 Short): 2047
XResolution (1 Rational): 1
YResolution (1 Rational): 1
ResolutionUnit (1 Short): None
DateTime (20 ASCII): 2001:01:11 18:50:28
Copyright (24 ASCII): (c) Space Imaging LLC |
33550 (3 Double):
33922 (6 Double):
34735 (32 Short): 1, 1, 0, 7, 1024, 0, 1, 1, 1025, 0, 1, 1,...
34737 (31 ASCII): UTM, zone 11 | Meters|WGS 84, |

As you can see, BitsPerSample == 16 and Photometric == 1, so it is grayscale image (which it is).  My co-workers can view the image correctly through libtiff (it converts the image to 8 bpp), but we need for us to view the image the same way like libtiff, but manually.  I have coded all for 8-bit images, but for 16-bit I cannot get the right display of the image (you can see the image, but the gray color of each pixel is way off).

Here is my routine to go through the 16-bit image data.  I wish I can send you my image to see what I am talking about, but the file size is over 190 mb and I do not have a website for someone to pick it up.  Unless you can suggest a way for me to do it, I will be happy if you can tell me about it.

int imageBlock = (SubBitmap->Width * SubBitmap->Height) - (SubBitmap->Width * Form3->POffset);
int StripOffsetSize = ImageInfo.VByteCountPerStrip[0];
BYTE *pBits = (BYTE *)malloc(imageBlock);
BYTE *TmpBits = (BYTE *)malloc(StripOffsetSize);
fseek(m_TiffFile, (ImageInfo.VStripOffset[0] + (ImageInfo.ImageWidth * Form3->LOffset)), SEEK_SET);
//Process data and spit out to file...
int block= 0;
int SubHeight = 0;
int SubWidth = 0;
int lineHeight = 0;
int curPix = 0;
for(int i = Form3->LOffset; i < SubBitmap->Height; i++)
size_t GoodRead = fread(TmpBits, sizeof(BYTE), StripOffsetSize, m_TiffFile);
for(int curPixel = 0; curPixel < (GoodRead / 2); curPixel++)
//Convert the 16-bit pixel value to an 8-bit value
unsigned short value16 = *TmpBits++;
value16 = value16 + (*TmpBits++ << 8);
pBits[curPix++] = (value16/257. + .5);
TmpBits -= GoodRead;
inputHeight = lineHeight; //Globel variable keep track of acutal height of image..
SubImage = BuildDIB(pBits, SubBitmap->Width, SubBitmap->Height, 1);
pBits = 0;
TmpBits = 0;
free(TmpBits); //Free memory

Where BuildDIB is a routine to make a BMP image object and returns the HBITMAP...well, here is the code as well:

HBITMAP BuildDIB(Byte *ASource, DWORD AWidth, DWORD AHeight, DWORD ABands)
// generate BMP/DIB handle from the raw image pixels
   BITMAPINFO bmi;                              // bitmap info structure
   Byte    �r