Reading EXIF without entire image

[till213]

Hi list,

can I extract EXIF data from an image without reading the entire image?

Currently I have something like this:

Code: Select all

    try
    {
        Magick::Image image(filePath);

        exif["DateTime"] = QString(image.attribute("EXIF:DateTime").c_str());
        exif["Model"] = QString(image.attribute("EXIF:Model").c_str());
        ...
    }
    catch (Magick::Exception &ex)
    {
       ...
    }

This works, but it takes too long (> 2 seconds per JPEG image, resolution ~ 2500x2000, which are on disk, so it really seems that the entire image is read; is this interpretation correct?)

Thanks, Oliver

[till213]

So I have done the following comparison with some photo JPEG images (around 2500 x 2000):

ImageMagick 6.3.2, Release, compiled with VS 6, quantum depth 8:

identify.exe -format "%[exif:*] myImage.jpg

Takes some time, about 0.5 seconds or more ("subjective measurement")

EXIV 0.15, Debug (!), VS 2005 Express (http://www.exiv2.org/)

exiv2.exe myImage.jpg

Prints EXIF data "instantly".


So I believe that ImageMagick (I am using the C++ API), as I have used it, really loads the whole image data. But at this point I am really only interested in the EXIF data.

Hence the question: Is there a way to extract the EXIF data only, without reading the whole image data (possibly with the C API/low level API)?

[anthony]

ImageMagick can not possibly handle all situations for all image formats. Especially in cases where you want it to ignore the image data which is the primary purpose on IM.

I suggest you look for a specific image file format tool for EXIF for TIFF. When you find one please let me know so I can include it on the IM Examples, File Formats Page.

If it was JPEG I would have suggested 'jhead', but for TIFF no one has reported to us a program to do this type of thing. Sorry it is out of the scope of the IM project.