How to generate a tiff file with meta data - objective-c

Question

I have to generate a tiff file with many images and meta data.
I found that it's possible to convert a png or a jpg to tiff here :
But how to add meta data ? it is possible with ImageMagic for iOS ?
thanks
Edit: finaly i installed ImageMagick on iphone, but i don't found how to create multipage tiff with magickwand .... it's possible also to use libtiff directly :
i found how to create a empty simple page in c code
char buffer[25 * 144] = { /* boring hex omitted */ };
TIFF *image;
char szFileName[512];
strcpy(szFileName, getenv("HOME"));
strcat(szFileName, "/Documents/");
strcat(szFileName, "output.tif");
// Open the TIFF file
if((image = TIFFOpen(szFileName, "w")) == NULL)
{
printf("Could not open output.tif for writing\n");
}
// We need to set some values for basic tags before we can add any data
TIFFSetField(image, TIFFTAG_IMAGEWIDTH, 25 * 8);
TIFFSetField(image, TIFFTAG_IMAGELENGTH, 144);
TIFFSetField(image, TIFFTAG_BITSPERSAMPLE, 1);
TIFFSetField(image, TIFFTAG_SAMPLESPERPIXEL, 1);
TIFFSetField(image, TIFFTAG_ROWSPERSTRIP, 144);
TIFFSetField(image, TIFFTAG_COMPRESSION, COMPRESSION_CCITTFAX4);
TIFFSetField(image, TIFFTAG_PHOTOMETRIC, PHOTOMETRIC_MINISWHITE);
TIFFSetField(image, TIFFTAG_FILLORDER, FILLORDER_MSB2LSB);
TIFFSetField(image, TIFFTAG_PLANARCONFIG, PLANARCONFIG_CONTIG);
TIFFSetField(image, TIFFTAG_XRESOLUTION, 150.0);
TIFFSetField(image, TIFFTAG_YRESOLUTION, 150.0);
TIFFSetField(image, TIFFTAG_RESOLUTIONUNIT, RESUNIT_INCH);
// Write the information to the file
TIFFWriteEncodedStrip(image, 0, buffer, 25 * 144);
// Close the file
TIFFClose(image);
So are there any c tutorial about how insert images Data in the created tiff file ?
and how create multipage tiff ?
thx

Answer 1

I have used LibTIFF - but not on iOS directly. But then, it is a plain old C library, so should be fine. I do note that the Apple Image I/O framework supposedly supports image meta-data (but again, I have not used this myself). See link here - but seemingly nothing for multi-page TIFF or bespoke tags, only standardised camera info tags...
However, in plain C, adding your own bespoke tags is usually performed most simply by modifying the core library and adding them to the main header file: tiff.h along with a few wrapper functions.
See section on "Adding New Tags"
And then you can refer/use them as you would other TIFF tags, e.g. what I have done to load in some embedded xml data:
TIFFGetField(lp_tif,MYTAG, &lp_xml)
Of course, you then have to ship/maintain your modified version of libTIFF (new "public" tags have to go through the process with Adobe).
The example you posted is fine for writing a single TIFF file (i.e set all the tags then write the contents of buffer to the file). For multi-page TIFF - it's one step further. You need to understand the concept if a Image File Directory (IFD). I would suggest looking at this link further to understand the use of the functions:
TIFFWriteDirectory()
TIFFReadDirectory()
NB: Properly, every TIFF file should have one directory to associate all the tags and image data together.
Finally, you can of course go one level even further! If you know the fixed structure of the TIFF file you want to create - simply write the bytes without even using LibTIFF.

Answer 2

In case it is an option for you to use a script for adding the meta data:
Use Phil Harvey's exiftool!
exiftool is a quite powerful, well-documented (and multi-platform) commandline utility to read and write meta data from/to lots of different file formats, including TIFF.