# RAW Vs BMP



## Done_Fishin

Out of curiosity what is the difference between RAW and .bmp (bit map protocol) if any ..

Edit .. maybe I should ask if this article covers the bases or not

http://djt3k.blogspot.com/2008/06/raw-vs-bmp.html

it seems credible .. I have always scanned and saved my photo's in bmp usually scanning at 600dpi although I could have done better, but thought that file size vs physical gain not worth the hassle.

edit2 .. I have moved my post from Yustr's "Upgrade" thread to this one, since it seems more appropriate. Just in case anyone had read it and got confused.


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## DonaldG

Done_Fishin said:


> edit2 .. I have moved my post from Yustr's "Upgrade" thread to this one, since it seems more appropriate. Just in case anyone had read it and got confused.


And I gave it its own thread :smile:


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## DonaldG

I am not sure I totally agree with his final comments about saving as BMPs etc...

My reasoning:
Once the image is in the camera's storage card, it will be set as either .JPG or RAW or both.

That is then copied (not opened & saved) over onto the computer's hard drive and also probably archived onto CD/DVD. The images on the HD/CD/DVDs will be identical in every respect to the originals in the camera.

Although I don't know sufficient about the protocols of BMP, it stands to reason that opening a JPG and or RAW and saving it as a BMP, some internal image file structure must change so that it can be read as a BMP.

Because the standard 'copy' process does not alter the file structure in any way, why convert it. To my mind, the conversion is just adding another process to the equation. If in some future time you need to work on the image, then is the time to do the format change.

Over the years I have been doing computer imaging, I have always adopted the policy of saving in the proprietary lossless format of the software in use when using a scanner. 

This has generally worked out well but on rare occasions has caused a problem incompatibility when changing software.

I have used Paintshop Pro since version 3 (on a floppy as a magazine cover disk) and saved as a .PSP then I converted to Photoshop at V6 and saved as .PSD This was working on the premise that the software native lossless format was the best for use with that software...

It will be interesting to hear (read) other folks take on the subject.


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## Done_Fishin

I Thought the other thread was a good one too :laugh: .. since it was an extension of the original theme but never mind .. The idea is to figure out what is going on 

From what the author says in the above link, RAW is extremely useful since it holds much more information than the eye can see .. In that I am assuming that he means information in the Infra Red and Ultra Violet spectrum's are also held in the photograph. Bitmap seems to restrict the amount of information that is held in the picture.

I assume again that the closest analogy to this would be seen when editing a photo.

I have taken some photo's in the dark that just seem to give a very dark image yet when adjusting the Gamma, Bright & Contrast in ACDsee we get a an idea of what we were not able to discern with the naked eye in picture 

BEFORE EDITING









AFTER EDITING 









Admittedly those pics were taken in jpg format and all I did was tweak the exposure settings .. but it is clear that a lot of information was captured in the photo that was not initially seen. You might need to be told though that at the end of the pathway is a gate and road though .. Original picture size was approx 1MB.


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## Done_Fishin

After spending a couple of hours searching the web, I found that this is not an original question.

RAW is RAW .. it's not a picture it's a collection of "pixel values" in digital format that is used to make a picture.
It holds a lot a lot more info than might be required to make a picture 
an 8MB RAW file 12 bit colour depth might transform into a 24MB TIFF file with only an 8 bit colour depth.
I read that it's comparable to a "digital" form of a negative. 

Once you have it, you can't actually use it to show anyone a photograph, you have to process it first to create a format that is a usable photographic format.
from RAW you can create any picture format you desire. You save your raw format files as raw since that is the format that holds all the information.

the use of RAW is comparable to recording sound on Video tape which has a much lower noise threshold and a much wider frequency spectrum than most other recording media. After which the sound is copied to Cassette tapes ( noisy), CD's and mp3's (lossy but better noise ratio), Vinyl (noisy with added wow & flutter) etc .. depending upon the requirements of the user or creator


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## zuluclayman

I think the main thing here is to recognise that RAW has all the information that the camera's sensor collected for an image - often way beyond what the human eye can see/differentiate between - thus if you want to save it as this then you will have available the closest to what the camera was able to detect.
When editing RAW images you have all the information available and are most likely going to save the resulting image in some recognisable file format which will involve some loss of information. 
Unless you are going to be exhibiting/distributing extremely large in size/high resolution images, most human eyes will not be able to discern the difference between the RAW file and the resulting (accessible file format) image.
One factor that has been left out of this discussion is the importance of colour management in your computer system - monitor, software, printer (if you choose to print your own images). The RAW image may contain all the information the sensor is capable of assimilating but if you edit this without correct colour management then the output will not match, in any way, the image seen (by the fallible human eye) on the monitor.


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