lossless format vs .jpg

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Pat

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I received an electronics club email with the following info:

******************************
"If you want maximum image quality, don't use JPG (.jpg) in your 
camera.  Use some loss-less format like TIF or BMP (ugh).  By 
definition, JPG gives up image details to minimize file size.  AND, 
that happens EACH TIME you save!  That means, if you have a perfect 
image saved in JPG and just want to tweak something (e.g. redeye), 
when you save the picture next time - you lose more image quality. 
If you save it as little as three times, you SHOULD see a visual 
degradation in the image.  None of this is true in TIF of BMP 
formats.  Once you have optimized your image, THEN you can consider 
JPG - ONCE - to achieve a smaller file size.

Of course, you camera might not offer a loss-less format - but I 
would be VERY surprised if that was true"

**********************

I have a Canon PowerShot SD550 Digital Elph.  I have several choices of size and resolution, but not format.  I think all the files are saved as .jpg.  When there are hundreds of pictures, or even dozens, I don't want to have to open each one and save as .bmp or .tif. 

Does everyone agree with the above info?  That every .jpg photo loses pixels with each save?  Any solutions?  Any further info?  Comments?  Suggestions?  Warnings?  How can a digital file lose info? 

--pat
 

rhmahoney

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Most of the time this is a non-problem. I shoot a 5 megapixel jpeg and limit myself to one burst of editing, if any. Jpeg is a lossy compression of data. Everytime you resave the image, more data is discarded. I get arround this by archiving the original image and going back to a new copy of any image I want to re-edit.
 

Pat

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rh:  I do the same.  Archive the original and play with a copy.  I rarely save on top of the original, unless it's a quick pic for an email. 

The write used the word "ugh" about .bmp and apparently prefers .tif.  Is that a common opinion?  I never work with .tif files.  No reason.  Cameras have always spit out .jpgs, and often I'll need .bmp for something in Windows. 

--pat
 

DougJ

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Hi Pat,

In addition to what RHM has said, let me add that I accept that information as correct although I've never tested it.  I accept it because I've read that assertion made by many different experts and I've never seen a contrary view.

So, what do I do?

I capture most of my images in the RAW format, but do, from time to time, capture as JPEGs in the highest resolution my camera allows me.

If I decide to do anything with a JPEG image the first thing I do is to save it in PhotoShop's proprietary format, PSD.  If you don't use PS, then use your editing program to save it as a TIFF.  Then do whatever processing you need to do or want to do, saving always as a TIFF.

I always print from a TIFF format and only revert to a JPEG format if I'm going to share the image electronically.

Ciao,

Doug


 

Pat

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Doug:  I have Photoshop Elements with this computer.  I'll check to see if it can convert files to PSD as it retrieves them from the SD card.  I sure enjoyed watching Photoshop work the first time.  It even cleans off the card.  Specifying the directories where I want the pictures can be a pain, but I've sort of got that worked out now.  It's a lot faster just to drag and drop the pile into the directory I want, but then I have .jpgs.

--pat
 

Chet18013

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If your camera allows you to shoot in RAW, you should always save in this format if you desire to preserve the original shot without any dedgradation from repeated viewing. If you plan to do any editing, it is recommended that you start with a copy of the RAW, thus always preserving the original RAW.  If you don't have a RAW  setting, I recommend you read this:

http://www.adobe.com/products/photoshop/pdfs/understanding_digitalrawcapture.pdf

Chet18013
 

King

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It has always been my understanding that you have to choose the amount of compression when tou use the jpg format.  If you choose the highest resolution, there is no loss, and as you increase the compression, you lose resolution.  The reason jpg is so popular with camera manufacturers is that you can get full resolution with less storage space.  Just never use the higher compression settings.
Art
 

DougJ

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Hi Pat,

Chet wrote:

If you plan to do any editing, it is recommended that you start with a copy of the RAW, thus always preserving the original RAW.

I agree.  My approach is to save my original (straight from the camera) images in a sub-folder to my "original images" folder.  My images through their various incarnations as I post-process are saved in sub-folder to my "adjusted images" folder.

Once I have a version that when printed I am satisfied with, (and I may have more than one of these for a given image because they are specificall processed to physical print size and resolution,) it is saved in a sub-folder to my "print images" folder.

Ciao,

Doug
 

ChinMusic

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RAW vs. jpeg:

Of course RAW has more information regarding the image.  The question is whether there is a practical difference.  Unless you are blowing up something to poster size, I think there is no practical difference.  I do sports photography as a hobby and I shoot jpeg all the time at the largest file setting.  If I were in a studio with the intention of making a huge poster/billboard, I'd shoot RAW.

For those of you with the capability to do both, try it.  See what the practical difference is.  You will find that on normal size prints you will be very hard pressed to tell which is which.

In my opinion, I want to be able to store more shots per card and to store more shots on my computer.  I don't use RAW.
 

Bob Zambenini

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ChinMusic said:
RAW vs. jpeg:

Of course RAW has more information regarding the image.  The question is whether there is a practical difference.  Unless you are blowing up something to poster size, I think there is no practical difference.  I do sports photography as a hobby and I shoot jpeg all the time at the largest file setting.  If I were in a studio with the intention of making a huge poster/billboard, I'd shoot RAW.

For those of you with the capability to do both, try it.  See what the practical difference is.  You will find that on normal size prints you will be very hard pressed to tell which is which.

In my opinion, I want to be able to store more shots per card and to store more shots on my computer.  I don't use RAW.

I have been following the various discussion here on raw vs. jpg and feel many people may be mislead and enticed into using RAW.

I have a pretty good history of being published and winning a few large competitions and I never shoot RAW.

First, today's JPG compression is so improved that there is virtually no difference with RAW.  But it  is important  in working with an image, that you don't resave it several times in jpg, as each time you do save it over you do lose a very small part of information. In editing I save to to new copy each time.

The main reason I don't shoot RAW is I shoot a lot of images. With anything moving I like a many of images to choose from because fractions of seconds can make or break an image.

I have attached an example. When I got home I had 6 images of this scene. But only in one did I have the Gondolier in the classic post. Without this its garbage.  I was shooting all day in Venice and my son, unknown to me, also had 4 images but none with classic pose.

The show print is 13x17 inches at 300 ppi and its a knockout in detail in the buildings and reflection on water.

Also, for PPI, I  save at 250 or 300. The main reason is that the human eye can't see beyond this detail. Some of us probably can't even do 200, if we are over 35 years old! Early on editors seemed to want a lot of ppi but now they seem satisfied with 300-400, as long as you have the total pixels to make up the size they desire.

If you are going to take a shot and sit around and play with it for a long time and if you have lot of time and computer storage and horsepower then go with RAW.

Here is a very good summary.  http://www.kenrockwell.com/tech/raw.htm

Ciao, Bob
 

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John From Detroit

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I do believe that every JPG save looses information, HOWEVER, you have to remember that a file copy is not a save, so when you transfer a .jpg from the camera to the computer, nothing is lost, if you never edit, nothing is lost if you edit, and do it in one session, very little is lost,  the losses come from multiple edits over multiple sessions.  If you plan on doing that make the first save in a losless format, edit in that format, and then do the final save as whatever floats your hard drive

Same for audio files,,, You record it as best your recorder can, either transfer to computer or save as WAV, edit as WAV (Equilize, increase/decrease volume, crop, special effects and so on) finally you save as whatever you want (IE MP3) but do all the "Work" as wav files.  I do more audio than video,  I often save as CDA or save as WAV on external media for safety as well
 

DougJ

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I have a suspicion I'm about to tread where angels fear to tread--RAW vs. some other file format for image capture.

Bob Z. makes the point:

I have a pretty good history of being published and winning a few large competitions and I never shoot RAW.

and he's not alone.  Many very good amateurs and professionals shoot in JPEG; many other shoot in RAW and JPEG; and some shoot principally, or only, in RAW.

So, what gives. 

For me the issue is not whether one format is better than another, but whether one format (RAW) offers opportunities for significant post-processing adjustments that the other formats don't, and whether you, as a photographer want, or need, those additional opportunities.

I'm reminded here of another thread in which Smoky wanted to improve a shot whose exposure, etc., made for an ugly pic.  Frankly, I don't think there was much that a photoshop pro could have done with the image, even with lots of time to do it. 

Surgeons admonish each other not to do any damage with the scalpel; photographers admonish each other to get it right first time in the camera.  My hunch is that Bob Z is a very good photographer getting at least one of his multiple shots right first time.  That makes Bob's regular use of JPEG a good choice for him.

So, what does RAW offer me?  I'm uploading two images (in JPEG because that works best in the forum) to show what is possible.  The first one "arlingtonRAWorig" is a very badly exposed shot.  My camera captured the image in RAW format and I've converted it to JPEG just as though my camera had saved it in JPEG format at the time I captured the image.

The second image, "arlingtonRAWadj" is the same captured image in RAW but using Adobe Camera RAW software (or now one could use the beta version of Lightroom) I converted the image to JPEG as though I had used a different stop opening, or shutter speed, or white point when capturing the image.  In other words, long after I was at Arlington I am in effect "retaking" the image and that is possible because the RAW format has that info stored in the file.

Now then, even though I try, the fact is that I'm not the best photographer going, so I like to shoot RAW so that I can improve my images when I failed to get it right first time.  I also like to have shot in RAW when the scene has a wider EV range than the sensor can handle.  That means that I convert the RAW image once to get the highlights right; then I convert the RAW image a second time to get the shadows right; and then I place both of these in the same file, on separate layers and blend them so that the result shows the shadows with their right exposure and the highlights with their right exposure.

Finally, for the curious, the quartet of butterfly pics (another thread) that a number of you have admired were shot in JPEG.  I had four that were good (the Bob Z approach) and so the image files could tolerate the post-processing I did (adjusting in LAB colour space, some channel blending, etc.).

Ciao,

Doug


 

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Pat

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I am assuming a general rule that the largest file size is the best format.? I can to that.? I have tons of storage space on the computer and backup systems and a 1gb high speed camera SD card plus three batteries, so capacity isn't an issue.

It was easy to set on my camera.  I did the combination of resolutions and formats that allowed for the fewest pictures on the card. 

--pat
 

Karl

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Doug, Here's your adjusted picture with a bit of sharpening added. It does show a bit of pixelation, but the contrast has, IMHO, been improved somewhat. Speaking of contrast, it appears your subject and background has a fairly narrow contrast range, so it doesn't use all 128 (or 256)  bits of brightness info to render the highlights and shadow detail correctly. If it were a high contrast picture, I suspect some of the detail may have fallen outside the brightness range and would be lost. Does that make sense? 
BTW: That's a fun looking plane - experimental, I'm guessing :)
 

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DougJ

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Hi Karl,

BTW: That's a fun looking plane - experimental, I'm guessing

I do believe the craft falls within the relatively new category of light sport aircraft--a step up from ultralight and a step down from the spam cans like Cessna 172 (and I owned my own for several years).  And yes, having seen it demonstrated, it is indeed a fun aircraft.

As for the pic,

Speaking of contrast, it appears your subject and background has a fairly narrow contrast range, so it doesn't use all 128 (or 256)  bits of brightness info to render the highlights and shadow detail correctly.

you must remember what I was trying to demonstrate: what the pic would have looked like if I had taken it as shot and saved in-camera as a JPEG, and what it might have looked like had I taken it with the correct exposure and saved it in-camera, all of which is about an advantage of capturing in RAW.

However, because it is a badly exposed image, when I ask the RAW converter to give me almost three stop openings of additional light, the noise that is always present in the shadows (and particularly so for underexposed images) is emphasised.  And then if you sharpen that without first reducing the noise, you sharpen the noise and it gives a pixelated look--and I'm guessing that you did not do any noise removal; would I be correct?

Were I to be working that image up for printing, I would first fix the noise issue (NeatImage), then I would crop to taste, and then I would work on the colour (in LAB space), and then I'd work on the contrast issue using probably both levels and curves, and then I would "capture sharpen" (the first round of sharpening), then I might do some creative sharpening / blurring (the second round of sharpening), and finally I'd sharpen for the specific resolution of the image at that point, and finally print using the ICC for the kind of paper on which I'm printing.

Thus the image I posted was a long way from a finished, fully post-processed image; and I did it that way only because I wanted to make as close as possible an apples to apples comparison between two JPEG images as captured by the camera's sensor.

Having said all that, I appreciate your comments.

Ciao,

Doug

 

DougJ

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I'd like to see what a full fix-up produces.

May be I'll do a full fix if I get time on my hands--there's nothing at the moment that I'd want or need to do a print of this--but if you want a sense of what full fixes look like, have a gander at the quartet of butterfly pics; mind you, those started off in far better shape than this little plane does :).  When I took that pic I was playing around with exposures just for fun.

Ciao,

Doug
 

DougJ

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Hi Karl,

Couldn't concentrate on other stuff tonight so played with the LSA aircraft file.

Make what you will of the results :).

Ciao,

Doug
 

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DougJ

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The results are nothing short of spectacular, especially considering what you started out with!

Thank you, Karl.  And yes, the little plane does indeed "pop out" from the background trees.

Ciao,

Doug
 
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