Author Topic: EXIF image data and what it does  (Read 1199 times)

Online TelePlay

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EXIF image data and what it does
« on: January 23, 2021, 10:28:11 PM »
Since the question came up again, I'll do this simplification of what has already been posted in this photo/image board.

The first attachment below shows the EXIF information attached to an image that was taken on an iPhone and not processed through a simple image editing program or the forum uploading security routine, the original image directly from the camera.

While there is a lot of information about the photo including that it was take nearly a year and a half ago, the key point is the box in red, the orientation recorded by the camera to be used by a digital device that will display the image. In this case, the image has to be rotated 90 degrees CW (clock wise) by the displaying software to show the image in it's correct orientation.

This is the EXIF information that is deleted from an image that is being uploaded to the forum through its security routine (a routine enabled to insure nothing malicious is uploaded to the forum) that removes almost all of the EXIF data including the image display orientation information.

This second image shows the EXIF data from a sideways image already on the forum. You can see most of the EXIF data has been removed by the forum security software and without the orientation information, the image displays sideways.

This third image is the sideways image from above. It was downloaded, opened in MS Paint, rotated and saved with a file name that adds it was rotated. This image now displays correctly on the forum as seen in the last image at this link

and the image of this rotated image is almost identical to the sideways image above, no EXIT data.

Advanced image editing software, that installed on smart phone and Adobe Photoshop, keep the EXIF data but regardless of what it is, it is removed by the forum security algorithm.

If the image can not be first transferred to a PC and process through a simple image editing program that removes the EXIF data, what you see in that software or on that phone will not be what is displayed after uploading it to the forum.

If the uploaded image is sideways, it can be downloaded to a PC, rotated and put back up and it will display correctly because the downloaded image no longer has the EXIF data orientation code that included the downloaded image. It was removed the first time the image was uploaded.

Downloading that image, rotating it and re-uploading it will result in an image that displays with the desired orientation. Downloaded images will always be free from EXIF data making rotation to correct orientation work every time. MS Paint is a very easy to use, fast way to rotate images. Other simple image editing software will also work.

Both of the last two images above have most of their EXIF data stripped away by the forum security software.

Just the way it is. Learn it, practice it and the membership will appreciate images that can be seen without turning their heads 90 degrees one way or another.

Online TelePlay

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Re: EXIF image data and what it does
« Reply #1 on: January 24, 2021, 12:13:43 PM »
To further explain image orientation, the following image is an example of a photo taken in 2014 and posted to an internet car site. The photo was taken with the camera in its horizontal position, as shown in the red box about 1/3 of the way down.

Since the original image was processed using Adobe Photoshop which, as said, does not strip away any of the META or EXIF information.

This photo if posted to the forum would have had the correct orientation, would display horizontally, but most of the META/EXIF data would have been stripped away, including the orientation code, by the Forum security processing algorithm. I this case, since the photo was take with camera in horizontal (normal) position, loss of image rotation information would not have made a difference.

I would think taking the same picture with a camera device in all 4 of its positions, horizontal, rotated 90 right, rotated 180 right and rotated 90 left and posting all 4 of them to the Forum in the "Member Photo Storage Area for Topic Related Linked Images or Other Such PERMANENT Use" board in a members own topic

to test the images would show which camera position produced the horizonal image without pre-posting editing and should be used to prevent sideways images from being uploaded without pre-uploading processing with a simple image editing software program.

What is unusual about this car image is that it is on the internet at a site with all of its META/EXIF data. Looking for an image on the internet that had this information attached was not easy. It seems almost all sites strip the META/EFIF data from images when uploaded leaving only the basic image information and nothing else. I would assume the other sites, and the Forum, realize that malicious code (viruses of any sort) can be imbedded in image code and have set their software to delete this META/EXIF information.

The following is but a few lines of code in the attached 200+ page text file "Car Photo Code.txt" (you need to save it to disk and open it up in WordPad or similar text processor program) needed to display one image.

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When all of the code in the text file is read by a computer device, this is the image that it will display.

I can read a few words in English that state document sections but the actual code is beyond comprehension. As you can see, it would be very easy for someone to insert a short viral code so that when the computer began to read the image code for display, the virus could be activated on the viewing the image. Changing an image code as such would not be seen in the image as displayed but could be read by the computer to install and pass on the virus. As such, the Forum has installed all security options and they will remain in place.

This has all been discussed in numerous topics and replies years ago but with a lot of new members experiencing difficulties posting images in their proper orientation, this topic is possibly a very needed refresher on posting images.

Sending a PM to me with questions is always welcome.

« Last Edit: January 24, 2021, 12:26:04 PM by TelePlay »

Offline FABphones

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Re: EXIF image data and what it does
« Reply #2 on: January 24, 2021, 01:18:40 PM »
...the actual code is beyond comprehension.

Wow. Even before I got down to that paragraph I was thinking what language is that. Its been a while since I last looked at a block of code but that is something else. Even every line aligned to the left making it tricky to follow its path. I must be really out of date. Or it was written by a self trained I dont need to follow the rules programmer.

Way too easy to hide something mal in that lot.

Thanks for the detailed info. Nice car btw.  :)
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Offline Key2871

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Re: EXIF image data and what it does
« Reply #3 on: January 24, 2021, 02:43:47 PM »
For those who post pictures from cell phones, I've found if I take a shot with the phone vertical and post it here it shows sideways. And I've not figured out how to change it in the post.
So I started taking shots horizontal, then they post correctly.
It wasn't always that way however. And the one thing that changed was my phone, my old phone would show vertical taken shots normally here.
Where as shots taken horizontal showed sideways.
Just a trick I use now. If I have older shots I rotate them in my phone so they are 180 degrees, and then they show correct, but they have to be turned a certain way or they show here upside down.