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coltson
n00b
Joined: 15 Oct 2005
Posts: 54
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 Posted: Thu Jan 03, 2013 2:34 am Post subject: eof error while reading TGA file |
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Hi, I have an tga file that I try to read in memory to make some modifications and then save it modified.
When I try to read the data from the Tga file into a memory block it reaches the end of the file. Here is the code:
| Code: | void TGAManager::readTgaData (char * memoryAdress, int imageSize) {
fileReader.read (memoryAdress, imageSize );
} |
The cause is that the calculated imageSize variable that I pass as second parameter to the read method is storing the wrong value. It should be of about 256KB as image visualization/edition software informs me, but it is calculating approximately 512KB.
Here is the code that calculates the image:
| Code: | Image::Image (int width, int height, int bpp) {
width = width;
height = height;
bitsPerPixel = bpp;
bytesPerPixel = bpp >> 2;
size = width*height*bytesPerPixel;
} |
And here is the code where I extract the width, height and bits per pixel from the file:
| Code: | bool TGAManager::extractImageFeatures() {
width = header[1] * 256 + header[0];
height = header[3] * 256 + header[2];
bpp = header[4];
cout << bpp << endl;
if (width <= 0 || height <= 0 || (header[4] != 24 && header[4] != 32)) {
cout << "The data about the file width, height or bpp is incorrect." << endl;
return false;
}
return true;
} |
The width and height are correct, so by elimination the problem has to be the bpp. I checked the tutorial I am following and it really is header[4] that I should kook for this information. I always get 32 when has to be 24 for the size of the file to be correct.
Any ideas about what is going on ? |
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Hu
Moderator
Joined: 06 Mar 2007
Posts: 21623
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| Posted: Fri Jan 04, 2013 2:54 am Post subject: |
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| A byte is 8 bits. The code shown for Image::Image sets bytesPerPixel to be bpp >> 2, which is also bpp / 4. Are you sure it is correct to divide by 4, rather than 8? |
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coltson
n00b
Joined: 15 Oct 2005
Posts: 54
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| Posted: Sat Jan 05, 2013 12:05 am Post subject: |
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| Quote: | | Are you sure it is correct to divide by 4, rather than 8? |
No it is not, the problem it is me, that have air between my ears. Thanks for the help anyway. |
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