How to save PGM bytes to a file

Asked Oct 08 '13 at 15:38

Active Oct 08 '13 at 16:25

Viewed 216 times

We are taking a UIImage and converting it to PGM as an 8-bit grayscale representation of the image.

The result is an unsigned char array of the bytes. I want to write this to a file to check what it has converted. When I do that using:

NSData *rawPGM = [NSData dataWithBytes:(const void *)somethingPGM length:strlen((char *)somethingPGM)];
NSURL *someurl = [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:@"temp.pgm"]];
[rawPGM writeToURL:someurl atomically:YES];

I get UTF-8 characters in the file, like ÚÛÜÝÝÜÛÚ××ÖÙØÚÛ instead of a set of integers 0-255 like a normal PGM file:

How do I save the unsigned char * to a file containing the integer representations of those bytes?

edited Oct 08 '13 at 16:25

asked Oct 08 '13 at 15:38

user2859267

Please post the code that's not working the way you expect. – Andrew Madsen Oct 08 '13 at 15:56
thanks Andrew, edited to show the code writing to the file, which I know is not correct. – user2859267 Oct 08 '13 at 16:16

How to save PGM bytes to a file

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