# Post Processing - getting rid of distortion



## tyrophagus (22 May 2010)

I thought I'd share a few screen grabs of a program I use for post processing.  These were test shots taken to try find the best position for my camera - there are horrible reflections so please ignore them.  This is not about the photos but about the techniques available to correct distortion. 

I have never had a needed to correct geometric distortions until I started taking photos of my tank.  I'm still trying to decide what works best.  I use Adobe Lightroom, Adobe Photoshop CS5 and DXO Optics 5.  

Photoshop can be used to correct distortion but you need a degree in graphic design....

I recommend DXO Optics, a stand alone piece of software that can be very useful in correcting both lens and geometric distortion in images.  It takes a few minutes to develop an image.

I always take photographs in raw format so that I'm working with a digital negative rather than trusting the camera's computer to adjust the raw data and produce a jpeg.  The camera applies all sorts of corrections like contrast, saturation, sharpening and brightness to the raw data and then produces a jpeg which is a compressed image format.  This means that the jpeg file is very limited in its ability to survive any form of post processing.  You end up trying to adjust a fraction of the original data the camera recorded.  Why save a jpeg image if you can save the original raw format with all its information intact?

All the above programs adjust raw images but will adjust (to a lesser extent) tiffs and jpegs.  DXO will adjust jpegs if you have no choice but to use them and correct distortion and geometric distortion. 






The above screen grab is DXO working as a plugin to lightroom (it works on its own as well).  The image on the left side is the original raw file and the image on the right is the corrected image.  The image on the left has some green dots at each corner of the tank which is the tool telling the program where the corners are that need to be arrange in a rectangle.

I think you can see from the original that I even took the photo from off center so the right of the tank is distorted to be higher than the left.

In the screen grab below I adjusted the white balance as the camera did not meter this correctly and the wall behind the tank has a green tinge.  I've also applied a crop to the tank which is why the space around the tank is slightly greyed out.





The following image shows what happens when you take a picture from above.  Using post processing can introduce artifacts and as you can see it does not quite work in this image as it creates and artificial depth and the back edges of the tank have not been corrected.





So here is a before and after.  The first image is a raw file with no adjustments





The 2nd image is with geometric and lens corrections applied as well as white balance correction.





Another before and after shot from above the tank








I've also used a new tool in the PS CS5 to automatically fill the reflection with what the program thinks should be there - pretty amazing as it took no effort, I just drew around the highlight and asked it to replace it.


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## ceg4048 (22 May 2010)

tyrophagus said:
			
		

> The camera applies all sorts of corrections like contrast, saturation, sharpening and brightness to the raw data and then produces a jpeg which is a compressed image format.  This means that the jpeg file is very limited in its ability to survive any form of post processing.  You end up trying to adjust a fraction of the original data the camera recorded.  Why save a jpeg image if you can save the original raw format with all its information intact?


1. Because RAW files are 50 gazillion megabytes which require investment in storage media and slows processing time, while jpgs are much easier to handle and store.
2. Because the camera makers algorithms for are more accurate than any third party program.
3. Because RAW files are proprietary and require proprietary decoders whereas jpg is a public format and are therefore always accessible to anyone who has not purchased a RAW viewer.
4. Because the difference in quality of an image between a RAW processed image and a high quality jpg cannot be detected unless the image is displayed at a huge size and if the observers nose is very close to the image.
5. Because 90% of what can be done in a RAW handler can be done with jpgs in Photoshop.
6. Because ultimately, the power, aesthetics and success of an image depends primarily on the two eyeballs and the grey matter located behind the viewfinder, not on whether the image was recorded in RAW vs jpg.

Cheers,


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## Mark Evans (22 May 2010)

ceg4048 said:
			
		

> Because 90% of what can be done in a RAW handler can be done with jpgs in Photoshop.



50% maybe Clive. I've noticed your not a RAW type of guy   think of RAW as co2, then you'll see what its all about. RAW does rule I'm afraid.

and for those who can shoot RAW, find software comes free.

be free from the matrix


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## ceg4048 (22 May 2010)

Yeah mate, I do have the RAW plugins for Photoshop and so I compared the results of a RAW processed images to the same images shot in jpg. Obviously it could have been a result of my ineptitude with the RAW handler, but I couldn't really see that much of a difference mate. So while there may be a lot more things that you could do with a RAW file, does it make a palpable difference in the final image? That's the question I always ask. RAW lovers need to show actual proof that the difference is significant because the rest of us aren't saying to ourselves; "I wonder how much better that image would look if only I had shot it in RAW?"

I love the little tutorial tyrophagus gives us, but at the end of it I immediately thought to myself; "What does the final image look like if he had shot it straight jpg?" I just don't think it's a no brainer to automatically answer the clarion call of RAW. There are just too many disadvantages without any clear benefits.

I guess I need to assume that whatever advantages a competent RAW processed image offers in quality is lost on an internet image formatting?

Here is one of my typical images. At 100% magnification (2 1/2 foot by 1 1/2 foot) it still looks fine, but of course loses some sharpness. Can anyone tell that this was shot in jpg? Can colour rendition, sharpness, detail or tonal variety be improved upon significantly by RAW?
You know me mate. I'm a "prove it" kinda guy. If improvement can be demonstrated then I'll switch. I can always prove the difference that CO2 makes, but advantages of RAW vs jpg has not really been proven. If the only difference is to one's workflow then it's a perceived advantage, not a real one.





Cheers,


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## Mark Evans (22 May 2010)

I see what your say Clive.   

for me, the only advantage RAW gives, is the ability to be free when in the field. The hassle free shooting pays dividends. No worrying about white balance etc.

relying solely on the camera to give you the correct colour tone is just not close enough for some, but to come home and adjust to pin point accuracy is great....I do lack in that department, but get closer with practise.

for the most part, JPEG V RAW at the scales we see....on the net, yes the difference is maybe minute, but when going to print, i've never took a JPEG to a printers but opted for tiff.

The biggest plus point for RAW V JPEG is white balance control. One of the most important parts of the image.Yes, much can be achieved in PS, but i've spent many a frustrating hour trying to correct an image, when i can now spend 30 seconds doing it...it becomes that easy

you really wouldn't of wanted to see what the camera thought was the 'correct' W/B for these, even with K set to the same output of the flash









Pros and cons for both sides Clive   and I fully appreciate what you say.


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## tyrophagus (22 May 2010)

Clive - Not everyone needs RAW.  RAW vs Jpeg has nothing to do with good photography so shouldn't mixed them up and I think you are.  If you want to avoid complexity, save storage space, don't have quality issues with your jpegs and don't want the flexibilty of RAW then stick to jpeg because you are not missing anything.



			
				Clive said:
			
		

> I love the little tutorial tyrophagus gives us, but at the end of it I immediately thought to myself; "What does the final image look like if he had shot it straight jpg?" I just don't think it's a no brainer to automatically answer the clarion call of RAW. There are just too many disadvantages without any clear benefits.



I was demonstrating software to show how easy it can be to correct distortion in either jpeg, tiff or raw files.  My little tutorial was not trying to demonstrate the superiority of RAW over JPEG.  You missed the point.

Most point and shoot photographers (I'm not implying anyone on this forum fits this category) don't need RAW because they are taking snap shots.  Most photographers (even professionals) don't shoot perfect jpegs but almost all professional photographers shoot in RAW if their workflow allows because they need the flexibility, and the "pixel peeping" quality.  

If you want to use jpeg then it's your choice to jettison most of the information your sensor recorded after the cameras done most of the post processing.  My fish tank images are not valuable so I don't care if I loose some data.  The images I want to sell are too valuable to throw away the negative. 

*quote="Clive" 1. Because RAW files are 50 gazillion megabytes which require investment in storage media and slows processing time, while jpgs are much easier to handle and store.[/quote]*

My raw files are 8mb and I produce jpegs that are 3 - 4mb and I have terabytes of cheap storage.    

*quote="Clive" 2. Because the camera makers algorithms for are more accurate than any third party program.[/quote]
*
The camera makers in camera algorithm (firmware) *is not more accurate* than the better stand alone desktop raw converters.     The camera firmware makes lots of assumptions, it applies tone curves, sharpens, adds saturation and adjusts white balance.  You really think a dinky computer on a camera can do this better than a human and desktop computer?  

*quote="Clive" 3. Because RAW files are proprietary and require proprietary decoders whereas jpg is a public format and are therefore always accessible to anyone who has not purchased a RAW viewer.[/quote]*

It's not ideal I agree.  You can covert them to the public format for raw files - .DNG, it's your choice but I don't bother.  You don't need propriety decoders to covert them, even windoze can convert raw files.

*quote="Clive" 4. Because the difference in quality of an image between a RAW processed image and a high quality jpg cannot be detected unless the image is displayed at a huge size and if the observers nose is very close to the image.[/quote]
*
That may be true, assumptions aside, but it's not got anything to do with dumping your negative in the trash and keeping a camera compressed copy of an image you may never get the chance to take again.

*quote="Clive" 5. Because 90% of what can be done in a RAW handler can be done with jpgs in Photoshop.[/quote]*

I don't agree with that.  Perhaps your personal experience reflects this but its not mine.  You have lost most of the information you collected on the sensor.  You had 68,719,476,740 possible colors to manipulate in from your raw file but you discarded 99.9% to leave you with 16,777,216 possible colors. 16000000 colors is close to the limit of what we can discern but when your computer does it's math as you adjust your sliders in PS do you not think this might make a difference to the accuracy of the computation? 

* quote="Clive" 6. Because ultimately, the power, aesthetics and success of an image depends primarily on the two eyeballs and the grey matter located behind the viewfinder, not on whether the image was recorded in RAW vs jpg.[/quote]*

I couldn't agree more!  Shooting in RAW vs jpg has nothing to do with the process of creating an exceptional photograph.

You will probably never see the differences on web images which have a resolution of 72dpi but I think you might if you printed A4 or greater.  

I tried to not to allow any bias to creep in    Yes these photos are very saturated and contrasty and yes you can't see a huge difference in the processed images but its there and if you printed them I know which one would look better.  The post processed images look very similar to the actual scene, the camera just can't cope with the dynamic range.

In camera jpg (no adjustments)




Raw -> jpg, (post processed in lightroom)




Jpeg -> jpg (post processed in lightroom)




Raw -> jpg (post processed in DXO)


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## tyrophagus (22 May 2010)

ceg4048 said:
			
		

> Yeah mate, I do have the RAW plugins for Photoshop and so I compared the results of a RAW processed images to the same images shot in jpg. Obviously it could have been a result of my ineptitude with the RAW handler, but I couldn't really see that much of a difference mate. So while there may be a lot more things that you could do with a RAW file, does it make a palpable difference in the final image? That's the question I always ask. RAW lovers need to show actual proof that the difference is significant because the rest of us aren't saying to ourselves; "I wonder how much better that image would look if only I had shot it in RAW?"
> 
> I love the little tutorial tyrophagus gives us, but at the end of it I immediately thought to myself; "What does the final image look like if he had shot it straight jpg?" I just don't think it's a no brainer to automatically answer the clarion call of RAW. There are just too many disadvantages without any clear benefits.
> 
> ...



Clive I think you could improve the dynamic range if you used RAW (but you have lost the data and cannot retrieve it) and processed the file properly.  The stem has no detail in the shadows and is pitch black, the bubbles are at the other extreme and quite specular, however they would be difficult to improve even with raw data.  Loss of shadow detail and the inability to recover it is one of the biggest drawbacks of lossy jpeg compression.

That does not detract from the image however which is very punchy and vibrant.  Did you do anything to this on a computer or did you just allow the cameras firmware to process the image?


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## ceg4048 (23 May 2010)

Hi mate,
            The lost detail in the stem has less to do with RAW v jpg and more to do with composition within the context of available lighting. This was a choice I made in the original exposure. If I wanted to pull data from that part of the shadow I could use the "Shadow/Highlight" function, but stem detail wasn't important to me in this particular shot. In fact just the opposite. The jpg was post processed in PS. A bit of sharpening here a bit of colour correction and "Levels" there. The colour balance is a custom setting I derived in the tank, so colour correction takes 30 seconds. This is tank lighting, no flash or studio jobs.

If you are selling images then there is every reason to maximize the quality. No argument there. But this fundamentally is my point. Most people don't sell their images, yet there is all this fanfare about using RAW. If people are not aware of the advantages/drawbacks, then they are simply following the bandwagon without ever challenging the reasons they are on the wagon.

I must apologize for dragging you off track with my response, and I hope you are not too upset with me (as if I were a gate crashing hooligan at a sweet 16 party), but in responding to my challenge you did exactly what we needed to see in the first place. If you're going to put value statements in your post (the bit that I quoted), you must justify them. Now, with the additional data you have provided, we can see the difference, or at least a typical difference, and each photographer can make his/her own value judgement on the results. 

Remember when everyone shot film? Pros used medium format and large format slides. Amateurs shot 35mm print film. Was there a difference in quality? Yes, absolutely, but only serious amateurs went through the trouble for the high quality because 99% of shutterbugs sent their film to the pharmacy and lived with the 3 X 5 prints. The quality was good enough and cost was low.

The digital analogy therefore is that jpg is usually good enough for most, vs RAW, which is for serious folk who want to squeeze that last ounce of quality from their images.

Cheers,


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## tyrophagus (23 May 2010)

nt


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## tyrophagus (24 May 2010)

Ceg I agree photographers who only shoot jpg probably don't need raw. I just like to maximise quality and raw allows that flexibility. This is not a discussion I wanted to have, I wanted to discuss with forum members a way to easily correct distortion. 

However some of the things you state as fact are from where I'm sitting just wrong.  From your posts on this forum I have loads of respect for your intellect and ability to explain things. Other forum members I think feel the same, and I think many would believe your statements.  

If you wanted to (I appreciate your original exposure was intentional), you could not get the same shadow detail in that stem from a jpg as you could from a raw in photoshop because the data no longer exists to manipulate.  You can't can't go back if you want to because you chucked out the negative.

In the good old days when people used film most photographers (and many professionals) used 35mm. Those who wanted to maximise the quality of their prints developed their own 35mm slides and prints in the darkroom. Those that did not sent them to the pharmacy.

Today's photograhers are no different. Those who really want to optimise the quality of an image in the digital darkroom use Raw, and those who are not fussed use jpg.


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## George Farmer (24 May 2010)

Thanks for the tutorial, tyrophagus!

Great discussion on jpeg vs. RAW too!


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## Dave Spencer (25 May 2010)

Of course, the subject is the only thing that really matters with an image. One of the most highly acclaimed images of all time is overexposed with a soft focus. My opinion is that if an image relies on the focus, dynamic range etc. then it will be a good picture at best, but nothing more. How many of Henri Cartier Bresson`s images are out of focus?

I shoot RAW because it is more forgiving of my inadequacies than JPEG.

Dave. 

P.S. Nice tutorial.


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## murph (25 May 2010)

I almost always shoot raw. It's that bit more forgiving. I find that it's key for consistancy in images, for example at a wedding the ability to have all shots 'the same' as it were I think you'd struggle if you were toshoot in jpeg.

When your shooting jpeg the camera does the thinking for you. It decides on White balance, whatever colour settings the in camera chip inputs and I think often over looked sharpness. The rest of the information, what would be included with a raw file is dumped and cannot be retrieved. Photoshop will only give you back so much before pixelation becomes an issue.

Raw is often touted as a 'digital negative' and all images require post processing to realise there full potential. I genuinly believe that. I like the fact that I can make raw adjustments preocess the file to tiff or jpeg an then go back to the raw if I decide I don't like it.

I think raw gives greater scope and flexibility to those that want or need it. But as already mentioned has draw backs and isn't as important as ability, composition and luck!


Now what to do with all those 25mb files of bad landscapes and blurry fish!


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## George Farmer (25 May 2010)

I shoot jpeg because I'm too lazy to post-process so much.  

Also my in-camera noise reduction with jpeg is excellent.

All of the photos you see of mine on the web are shot jpeg.

Each to their own!


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## Graeme Edwards (25 May 2010)

I never shoot jpg any more. I did and when comparing it to PS RAW converter, I have much more controle and better results than faffing about with jpg tweeks. It just isnt the same.

However, if your a point and shoot type of person, then jpg off the camera can be very rewarding, but i dont think it gives the best controle or final image quality.

if its a great shot, its a great shot, no matter how it was processed.


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