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Mar 16th, 2009

Re: wrote to binary file, but...

BTW, in this case im using just rgbb[0] because im using a PBM file, with is a black and white and just use one bit per pixel, so i dont need rgbb[0] rgbb[1] rgbb[2]..but i keep the array because my program can open all types of pnm files(ppm, pbm, pgm, ascii and binary modes)
With the ascii files im having no problems..

Icebone1000

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Mar 16th, 2009

Re: wrote to binary file, but...

From what you posted earlier it still looks like rgbb is uninitialized. Do you write rgbb in text files too?

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Mar 16th, 2009

Re: wrote to binary file, but...

Click to Expand / Collapse Quote originally posted by Ancient Dragon ...

From what you posted earlier it still looks like rgbb is uninitialized. Do you write rgbb in text files too?

For text files I use the int rgb[3]....
I dont get very well what do you mean, I do not initialize rgbb with default values, i just start use it when reading the pixel map from the original file:

C++ Syntax (Toggle Plain Text)
readPNM.read(&img_pix[i].rgbb[0],1);
readPNM.read(&img_pix[i].rgbb[0],1);

Icebone1000

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Mar 16th, 2009

Re: wrote to binary file, but...

At this point I think you probably need to use your compiler's debugger, put a break point on that write line and inspect the value of that array. You have only posted one line from your program so its pretty impossible for anyone to tell you the solution to the problem. Possibly its not that line at all but somewhere else in the program, such as memory corruption.

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Mar 16th, 2009

Re: wrote to binary file, but...

It would seem impossible for your original code (in post 1) to write more than width * height + 25 bytes (give or take a few bytes for different widths since you are writing these as text), so if you are getting 8 times this many bytes your problem must lie elsewhere. You need to attach your (minimal) program and data file.

nucleon

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Mar 16th, 2009

Re: wrote to binary file, but...

Click to Expand / Collapse Quote originally posted by Icebone1000 ...

using this :
C++ Syntax (Toggle Plain Text)
writer.write(reinterpret_cast<char*>(&img_pix[i].rgb) ,sizeof(img_pix[i].rgb));
writer.write(reinterpret_cast<char*>(&img_pix[i].rgb) ,sizeof(img_pix[i].rgb));
the file gets 10,7 MB o__o"
using this :
C++ Syntax (Toggle Plain Text)
writer.write(reinterpret_cast<char*>(&img_pix[i].rgb[0]) ,sizeof(img_pix[i].rgb[0]));
writer.write(reinterpret_cast<char*>(&img_pix[i].rgb[0]) ,sizeof(img_pix[i].rgb[0]));
the file gets 3,4 MB ..
using this:
C++ Syntax (Toggle Plain Text)
writer.write(&img_pix[i].rgbb[0],sizeof(img_pix[i].rgbb[0]));
writer.write(&img_pix[i].rgbb[0],sizeof(img_pix[i].rgbb[0]));
the file gets 914KB
using this:
C++ Syntax (Toggle Plain Text)
writer.write(reinterpret_cast<char*>(&img_pix[i].rgbb) ,sizeof(img_pix[i].rgbb));
writer.write(reinterpret_cast<char*>(&img_pix[i].rgbb) ,sizeof(img_pix[i].rgbb));
the file gets 2,67 MB
using this:
C++ Syntax (Toggle Plain Text)
writer.write(reinterpret_cast<char*>(&img_pix[i].rgbb[0]) ,sizeof(img_pix[i].rgbb[0]));
writer.write(reinterpret_cast<char*>(&img_pix[i].rgbb[0]) ,sizeof(img_pix[i].rgbb[0]));
the file gets 914 KB

It seems that you are desperately trying various ways to write the file.

Maybe relax and try to master e.g. a binary .pnm file of a very small size, say 2x2 pixels hence being easily viewed in any hexeditor at a glance (notepad and wordpad surely are poor choices for checking the files' content).

Try for example the following struct for reading/writing

C++ Syntax (Toggle Plain Text)
struct Pixel
{
    // 3 bytes represents a single pixel
    unsigned char rgb[3];
};
struct Pixel
{
    // 3 bytes represents a single pixel
    unsigned char rgb[3];
};

Then when you read in the file you might

C++ Syntax (Toggle Plain Text)
 
// ... code here to read in the file's header ...
 
// allocate enough memory to read in rest of the file
const int pixels = width * height;
Pixel * p = new Pixel[pixels];
 
for(int ii = 0; ii < pixels; ++ii)
{
    // read 3 bytes at a time
    if( ! file.read(reinterpret_cast<char *>(p[ii].rgb), 3))
    {
        // should not happen, handle error ...
        break;
    }
}
 
// all done
// ... code here to read in the file's header ...

// allocate enough memory to read in rest of the file
const int pixels = width * height;
Pixel * p = new Pixel[pixels];

for(int ii = 0; ii < pixels; ++ii)
{
    // read 3 bytes at a time
    if( ! file.read(reinterpret_cast<char *>(p[ii].rgb), 3))
    {
        // should not happen, handle error ...
        break;
    }
}

// all done

Then to write the file, you can iterate over the array issuing

file.write(reinterpret_cast<const char *>(p[ii].rgb), 3)

Remember that the second parameter to both read() and write() determines how many bytes each I/O operation involves.

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Mar 18th, 2009

Re: wrote to binary file, but...

Im attaching a .zip file with the cpp and the image files im using to test the program..**

mitrmkar, but I think this is exactly what Im doing now, I tried with unsigned char and the method you said, and got the same 914KB result..

"determines how many bytes each I/O operation involves."
In the case of a pbm file, the map of pixels is just one bit per pixel( black or white)..

I still dont get how can the problem come just AFTER all the writing (or
reading)..?

Edit: Ah..I dont know how I can see whats going on by debugging it, since the array is dynamic allocated I cant watch it, and I dont have idea of how can I check the fstreams...

**Damn, Im getting upload error with the attachment of the file, is this temporary or I have problems?

Last edited by Icebone1000; Mar 18th, 2009 at 9:06 am.

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Mar 18th, 2009

Re: wrote to binary file, but...

C++ Syntax (Toggle Plain Text)
+		rgbb	0x0044714c "øÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍþÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ¸ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ"	unsigned char [3]
+		rgbb	0x0044714c "øÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍþÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ¸ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ"	unsigned char [3]

Hey, look this..thats a watching to img_pix[10000] on the reading momment...Im imagining it are getting right the one bit it suppose to, but since i have a byte on rgbb[0] it let the empty spaces after the bit with junk..And when Im writing to a new file, it writes just the bits, and put all this junk just after it??...Am Im imagining too much?

Icebone1000

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Mar 18th, 2009

Re: wrote to binary file, but...

Click to Expand / Collapse Quote originally posted by Icebone1000 ...

C++ Syntax (Toggle Plain Text)
+		rgbb	0x0044714c "øÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍþÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ¸ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ"	unsigned char [3]
+ rgbb 0x0044714c "øÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍÿÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍþÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ¸ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ ÍÍÍÍÍÍÍÍÍÍÍÍÍÍÍ" unsigned char [3]
And when Im writing to a new file, it writes just the bits, and put all this junk just after it??...Am Im imagining too much?

Now remember the second parameter to write() , that specifies how many bytes are written.

PS. Maybe you could try to re-post your code

mitrmkar

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Mar 18th, 2009

Re: wrote to binary file, but...

I attached the files.

"and put all this junk just after it??"

I get it, but it puts the junk after ALL the bits, not just after each one, that is what Im not understanding.
And how can I say to read and write to get just a single bit?

Attached Files

myPNMtest.zip (362.7 KB, 9 views)

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