[imamkomc]

Hi all,

I have a problem to read and write file image in extension (*bmp, *jpg,*ico and so on). if i use order fgetch(), it can't be read the character from image and only can be read file character as A...Za..z0..9..etc.
what are the order to read file image in C/C++ ?

Thanks.
ImamkomC++

[NickDMax]

Well you should be able to use fgetch() to read in a byte of data (not just alphanumeric characters) but you have to remember that the data that you get is not going to be very pretty to print to the screen... its data not ascii text.

You can find lots of information that the formats that that data will take for the various image formats. Each format is different and so you will want to either deal with each image type individually, or you will want to use a library which abstracts the finner points of image file formats. Most operating systems/platforms should support some native handling of images. For example Windows has lots of functions for loading BMP, ICO, and JPG files. Although Linux/Unix don't nativly handle such images, there are lots of associated libraries that do.

[imamkomc]

Hi all,
i will try to explain my post about read image file.
it's part of program to open a file :
***************************************

...
		 FILE *input;
   	 char get_char;
		 input = fopen("test.txt", "r");		
		 while((get_char=fgetc(input))!= EOF){		 	
				cout<<get_char;	
		 }
   	fclose(input);
...

how to open or read image file ?
i have an image e.g. with extension *.ico
if i run to open with notepad in windows than see many character, but
if i using part program above to read all character from image file, than it doesn't to read all.
What's up ?
only fews character can be read. example i have name of file "animal.ico", and i try to implementaion
part of program like this :

...
		 FILE *input;
   	 char get_char;
		 input = fopen("animal.ico", "r");		
		 while((get_char=fgetc(input))!= EOF){		 	
				cout<<get_char;	
		 }
   	fclose(input);
...

actually, if my second program is true than automatic all charakter can be read till finish.
help me.

regard,
ImamkomC++.

[couta]

i have the same problem :s anybody can help me?

[Lillefix]

Have a look at this thread, it might help you:
http://www.vbforums....p/t-261522.html

[matthew180]

I would suggest you use a library like FreeImage or ImageMagick unless you are doing something *very* specific with the raw image data (even then I'd use one of those libs to load the image and just access the buffer directly).

If you must do it yourself, then I would do something like this:

1. stat() the file to get the size
2. use malloc() to allocate a byte (unsigned char) buffer large enough to hold the image (or use mmap() if the image is very large)
3. use open() and read() (*not* fopen() or fread()) to load the image into the allocated buffer
4. close the file
5. do whatever with the image data in the buffer
6. when you are done, release the buffer with free()

Matthew

[couta]

i have this and don't go to more then some lines.. not finish the file

   
int file;
 file= open ("aa.jpg", O_RDWR , 0600);


	int caracter,tam;
	unsigned char byte[1];
	
		while( tam=read(file, &byte, 1)>0)
		{
	 
		  cout << byte;
			}

what are wrong because with txt file works fine

This post has been edited by couta: 26 January 2009 - 11:03 AM

[matthew180]

Why are you trying to read the file 1 byte at a time? Also, keep in mind that the image is binary data and you can't print to a terminal the full byte value range (0 to 255) since a terminal interprets byte values less than 32 as control characters, and byte values above 127 will vary depending on the terminal you are using.

Use stat() to get the file size and read the whole file with a single call to read()...

Matthew

[JackOfAllTrades]

You can't display/manipulate binary data as a string. A binary file may/will contain embedded NULL characters, which will be interpreted as the end of the string, making all string related functions stop at that point. It might be easier to tell us what it is you're attempting to do.

[NickDMax]

HexDump is a program I write to display the contents of a file. This will display all of the bytes in a jpeg file.

Hexdump of course only reads in data into a buffer that is 16x64 = 1024 bytes -- much smaller than the size of a normal jpg. To determine the size of the buffer you will need you can do one of two things:


#1 you can actually use the data from inside of the file (the jpg knows how big it should be).
#2 you can can seekg() to the end of the file and then tellg() tell hoe many bytes are needed.
#3 you can use an OS-specific function that returns the file size.


Though if you are only interested in the data at a specific point in the file, you can just seekg() your way there, and NOT read in the entire file... you don't HAVE to load the whole thing into a buffer.


Note you can not use C-Strings with binary files, you CAN use C++ std::string which does not really care too much about nulls.