New answers tagged metadata
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If you can see bokeh circles of faraway light sources, they appear like paper disks of diameter f/a (optical focal length divided by aperture number) would look when placed in the focusing distance. That gives you a rough manner of estimating the focusing distance based on visual artifacts. It requires such artifacts to be prominent, of course, so you are ...
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If you want to avoid compression then raw files are your best choice when available.
A camera recorded tiff isn't any better than a jpeg... the image is still processed and data lost/converted in the same way as an 8bit color jpeg; only the resulting image data isn't compressed which makes the files even larger than raw files.
I would use jpegs with very low ...
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Post camera processing can cram in as much additional meta data as desired, so I assume you are interested in what the camera produces directly.
In general, RAW is going to have everything the camera offers. Conversion to another format isn't going to create more meta data. It's certainly possible that a given manufacturer may only insert selected meta data ...
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One very good option is to use TIFF format as it support EXIF, IPTC. Also you can store the images in uncompressed, lossless compressed, lossy compressed form. You can have multipage files. As benefit TIFF support 8,16,24,32 even more (for some colour space/compression) bits. And it support RGB, CMYK, YCbCr colour spaces.
But be aware usually the size of ...
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Since you know the size of the aruco markers, the focal length of the lens, and the sensor size (or the effective focal length in 35mm terms), you could use the recorded size of the markers w/in the image to determine the recorded FOV, and therefore the distance at which they were recorded.
Various calculators for determining image aspects (distance): http://...
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Some cameras record the focusing distance. But given the wide DoF of smartphone cameras I doubt this has any usable accuracy (assuming they focus at all).
For exposure, some cameras (my DSLR) output the measured EV in the EXIF while others (my phone) don't, but all output the aperture, exposure time and exposure bias, if any, from which you can recompute the ...
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If the camera signs the image, then you can prove that the image hasn't been altered since it was taken by that particular camera.
In many cases, we apply some post processing. And just using another RAW converter, such as Adobe Camera Raw or Capture One is also post processing in that respect. The file you distribute did not originate from the camera.
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The GPS data can be very revealing (they can give your address for instance) so for safety many applications now remove them.
On my Android phone, this is an option (set by default) in the Photo Gallery app where GPS data are removed when the photo is sent out using the application's "Share" function (which is how you usually send things to the ...
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By looking at the exif data, it's possible to know if the image has been developed in lightroom, or comes straight form the camera as a jpeg. This can also be faked.
Now, if you take a picture, then look at the result on the camera LCD, you can check the exposure, histogram, white balance, etc. They you can adjust settings and take another picture. ...
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An additional thing to take into account is the code that creates the jpeg has an identifiable signature. The way Photoshop writes the jpeg will be different than the way Corel will write it. Exiftool, for example, has a JPEGDigest tag, which is defined as:
an MD5 digest of the JPEG quantization tables is combined with the
component sub-sampling values to ...
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Well... It occured that i have automatic upload of photos to cloud. Somehow, for some reason - it removes (at least GPS data). Im really sorry for bothering You all - and I have spent definicely too much time today trying to find GPS data within files where it does not exists...
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In general the software on most cameras does not support this, but in theory it is definitely possible. The camera could directly encrypt the image with a public key and since it can only be decrypted with the private key, that could be held only by whoever needs to verify the images. For more details on what is meant by public and private keys, look up ...
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I've looked at your photograph and it really does seem like the GPS data is being zeroed out, i.e. stripped, from the image as it is being exported from your phone. If you can only see the image GPS information in the built-in image viewer tool, is it possible that the built-in tool is accessing a different version of the image file?
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Submissions for these types of contests, and even some news agencies, require photos to be submitted as straight-from-camera JPEG files, not as exports of RAW images. This is usually enough to satisfy the submission requirements.
Most of the time, people trying to skirt such rules by faking EXIF data, tend to make a mistake somewhere, that is a tell-tale ...
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Being slightly harsh, competition rules like that show that the organisers don't really understand how modern cameras work. A very high level and simplified view of how a camera makes a image (JPEG):
Light hits the sensor. Every pixel on the sensor produces an electrical reading which corresponds to the amount of light hitting it.
The camera converts those ...
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