ExifTool Forum

General => Metadata => Topic started by: ditimem on October 26, 2021, 03:08:50 AM

Title: Flash.
Post by: ditimem on October 26, 2021, 03:08:50 AM
Hi guys.
Sorry if my English is difficult to understand (because English is not my native language).
I'm new to metadata and hope someone can help.
1. I try to copy all data from image A to image B (-TagsFromFile), But when I check, it doesn't have Flash tag, and I try to tag Flash in the image tag, but it fails :(
  . exiftool -Flash=1 C:\Users\thieu\OneDrive\Desktop\Test.jpg
2. I want to make my photo exactly like iPhone data. Is there any better software or code?
Thanks, everyone.
Title: Re: Flash.
Post by: Phil Harvey on October 26, 2021, 08:25:32 AM
I'm guessing you are talking about the EXIF Flash tag.  "1" is not a valid value to write for this tag.  Try writing "Fired".

But this tag should be copied when copying all tags.  Your command should be something like this:

exiftool -tagsfromfile A.jpg -all:all B.jpg

However, that won't copy improperly formatted or unwritable tags.  In this case you might try copying the EXIF as a block to see if this is any better:

exiftool -tagsfromfile A.jpg -exif B.jpg

But without seeing a sample image, I can only guess about what is happening.

- Phil
Title: Re: Flash.
Post by: ditimem on October 26, 2021, 10:43:02 PM
Hi Phil Harvey. Thank you for taking the time for me. I am very happy and worried that you do not understand my question.
I tried it, and it works. If yes, I would like to ask one more question. Is there a way to make it impossible for other systems to check the edited photo? I searched the forum before asking.
Then find jpegdigest .
I check the original image:
JPEG Digest : Unknown (f3235a7d187d083b7b7ead949653f730:221111)
How to encode md5 like that?
Thank you for taking the time for me. Wishing you the best of luck in life and health. :D
Title: Re: Flash.
Post by: StarGeek on October 27, 2021, 12:21:30 AM
Quote from: ditimem on October 26, 2021, 10:43:02 PMIs there a way to make it impossible for other systems to check the edited photo?

Not really.

QuoteThen find jpegdigest .
I check the original image:
JPEG Digest : Unknown (f3235a7d187d083b7b7ead949653f730:221111)

The JPEGDigest isn't what you think it is.  It's "an MD5 digest of the JPEG quantization tables is combined with the component sub-sampling values" (see the JPEGDigest entry on the Extra tags page (https://exiftool.org/TagNames/Extra.html)).  This is basically a "fingerprint" of the program that encoded the jpg.  Every program encodes differently depending upon the source source code.  So an Adobe program is going to encode a jpeg differently than a program based upon the original Independent JPEG Group's library code.  All exiftool is doing to get this is computer the digest and compare it to the list of known hashes (https://github.com/exiftool/exiftool/blob/master/lib/Image/ExifTool/JPEGDigest.pm).  If it doesn't match, as in your example, it returns "Unknown".