Manipulating images and RAW image format - Queries

logistopath

logistopath

Molar Police
Staff member
Super Mod
Basically, I'm looking at ways to identify manipulated images. Please help me with the following queries:

1. Is it possible to manipulate a RAW image and still save it as a RAW image again?
2. If yes to Q.1, then does the edited RAW image store all information regarding what editing has been done?
3. In what way can an image manipulation be identified? By manipulation, I'm just referring to global changes made (i.e applied to the entire photo and not just a part of it) in brightness & contrast, colour level adjustments, etc.

I'm hoping to find some answers to my queries here. ;)
 
dont know about the first 2 questions, but doesnt edited image store original exif data and also the edited date and time in the properties. I assume it does store the edit time and date in properties.

ps edit : and iirc psd and tiff formats do store information about what changes applied and in which order.
 
1) A RAW file is your negative. It cannot be 'manipulated' by itself (like a JPG or TIFF)

2) Whatever changes you make (brightness, tonality, sharpness etc.) will be recorded within the RAW or separately, if you're using ACR. The original file will not be affected, but your specified changes will reflect in the output format. The changes can, however be used for direct printing etc, other software will take advantage of the capability of the RAW format to do so. You can always revert the RAW to its original state.

3) Usually, the out of camera RAW will need to be enhanced. For example, in the case of a canon RAW, I run it through DPP, and DPP will apply my picture style to the RAW (vivid or portrait or landscape or other setting), and will show me the preview. I can then make changes to the brightness or whatever settings I chose to. After saving the JPG, I might need to tone it further in GIMP or PS (unsharp mask, curves etc). You cannot easily tell if a photograph's basic properties have changed.

Just curious, why would basic manipulation matter, when its routine, and in some cases even necessary to get the best out of a particular photo? :)
 
Thanks for all the detailed replies. As some of you might be knowing, I am basically a pathologist. I am actually doing a study to find out if manipulated digital images yield a different diagnosis from pathologists, than original unmanipulated ones. I will be presenting my findings in a conference, and when I do so, I would like to offer some suggestions on how to identify and avoid manipulated images. This should explain my queries. :)

So a RAW image cannot be manipulated and stored again as a RAW. That makes it the absolute original, right..?
 
A RAW file can be copied to multiple locations of course, or renamed within the same folder, and you can apply different settings (recipes according to canon) to each individual file. You can save those individual setting files to disk to apply to other RAW files as well (for the same look or so).

To answer your question though, the RAW file will retain its data regardless of what settings you change through software. It is the image that the sensor recorded.
 
thanks ak3d for the info.

@logistopath : pleasure to help. BTW I never knew you were pathologist, nice to see one more medico here, i am an ENT surgeon.
 
Back
Top