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Saturday
Nov012008

Istockphoto Diary #3: One From Ten (Understanding Artifacts) 

It may not seem like it, but I think I'm getting somewhere. Among the batch of rejections, I got a great email that had a portion of a rejected picture - and I finally understand what Istock means when they say "This file contains artifacting when viewed at full size."

Lets have a look at the accepted photo, a few of the rejections, and a closer inspection of the artifacting issue.





Wooden Gate Detail Against Blue Sky: Accepted.



Note: There are no really "hard" edges in the above photo, the wood of the gate provides a more gradual transition to the sky.

Rejected: We're sorry, but we did not find this file suitable as stock. With the rapid growth of the iStock collection, we give valuable consideration to each file but unfortunately cannot accept all submissions.



Rejected: This file contains artifacting when viewed at full size. This technical issue is commonly created by the quality settings in-camera, in post-processing or in RAW settings. Artifacting may be the result of other factors such as excessive level adjustments.



Rejected: This file contains artifacting when viewed at full size. This technical issue is commonly created by the quality settings in-camera, in post-processing or in RAWsettings. Artifacting may be the result of other factors such as excessive level adjustments.
We found the overall composition of this file's lighting could be improved. Technical aspects that can affect the overall quality of lighting are: flat/dull colors, blown-out highlights, harsh reflection, shadows or lens flares. These can all limit the usefulness of a file.




Rejected: We found this file over filtered from its original appearance/quality.
This file contains artifacting when viewed at full size. This technical issue is commonly created by the quality settings in-camera, in post-processing or in RAW settings. Artifacting may be the result of other factors such as excessive level adjustments.




Ok, so Scout, who reviewed this photo, sent me a section of the photo that he wasn't happy with, and this has opened my eyes to what I'm dealing with in terms of Artifacts:




Look along the edge of the lamp post - see the fuzzy transition to the sky, almost like a halo?

Now lets look at a similar crop from the original, without a pass from Noise Ninja:




The original, without a pass from Noise Ninja, has a much better transition from the lamp-post to the sky, but obviously there's a lot more noise in the sky itself.

This indicates that Noise Ninja could be causing my artifacting problems - or to be more accurate, the global application of Noise Ninja is causing the problem. I should use Noise Ninjas masking capability to shield the part of my photographs where artifacts could occur, and let it work it's magic on the other areas.

I've resubmitted the photo, using the original straight from the camera, so it'll be interesting to see whether it gets accepted, or whether it will be rejected due to noise. Watch this space!

Conclusion

Getting things right in camera - framing, straight horizons and verticals, ISO, shutter-speed, etc is the way ahead. Because I shoot in .jpg, I need to avoid having to open and re-save the image, which in itself causes artifacts.

It seems that my use of Noise Ninja to reduce overall noise (especially the "speckling" in the sky) was a mistake - I need to use the plug-ins masking features to only apply it to the right areas.

So for the next batch of similar photos I'll be trying to only upload images straight from my camera (apart from rotating), and I may even turn down my cameras in-camera sharpening to "soft". We'll see.

ps - Thanks Scout for including the dodgy segment of my photo!

Cheers, Rob.

Reader Comments (7)

Hi Rob,

Excellent share as always.
You have unfortunately hit along a few 'bumps' on your travels!

I recently have found the whole issue of 'quality' somewhat disparaging in the last couple of months and have pushed my camera through many tests to find out where the fault lies. The main issues I have found can all be attributed to the sensor size of my camera. Not having hundreds of pounds at my disposal to upgrade my camera to one with a larger sensor, I have looked at ways of working around this.

I wondered if you've ever studied the physiological and psychological effects of actually 'seeing'? Our eyes are terrible on their own for a sight mechanism with a simple 'meniscus' lens, (and refactive cornea), and a poor biomechanical sensitive area. The image that our eye recieves is not transmitted to the brain as an image, the neural activity that is stimulated by the image on the retina represents the object to our brain.
The actual area of focus is a very small 1.7 degree 'sweet spot' over our fovea with a rapid deteriation in both focus and colour from there. (Over all we have roughly a 240 degree angle of vision). Our field of vision is 'filled' in by our brains by rapid movements of our eyes, (saccades and micro-saccades), which makes up the final image in our brain. I won't go into more detail as it gets rather lengthy from there!

A common 'Amateur' mistake with photography are 'bullseye' pictures, where the subject of interest lies smack bang in the middle of the picture. The viewer instantly recognises the image, (shape, form, colour), and then tends to dismiss the image, (minimal saccade required). When the subject is placed off centre, the viewer is now forced to make a saccadic scan to build up the picture, which in turn holds the viewers attention for slightly longer.
You already know this principle, it works best approximately 1/3 away from the centre of the 'frame'. (Rule of thirds!) Much more than this, ie. more to the frame edge, we either miss it completely, or notice it and it becomes an annoyance.
However due to our brain also linking 'emotive' content and memory, 'bullseye' pictures of certain subjects have an appeal in common. (Kittens, puppies, flowers, etc. etc. you know the stuff.)

Now that you realise you know this, I'll move on a bit. Despite our eyes poor abilities, between them and the brain we are very responsive to different levels of light. (Approximately 20-24 stops - considerably more than our cameras!) Our cameras however can produce just over 16 million colours whereas we recognise some 10 to 14 million. A full digital colour swatch looks to us as a smooth transition - until you limit the colours. Due to our sensitivity to luminosity and the limited steps available in one digital colour, we notice these steps. The best example to use is a digital sunrise/sunset, (properly exposed, with little or no jpeg artifacts), and due to the spread of colours, (white, yellow, orange, red, purple), it looks great. (Check the views on sunset/sunrises!). It however looks awful at limited resolution, overexposed or heavily compressed as we now see the limited steps in the colours. The same is true when you limit the colours used, transistions become more apparent, including noise.

This moves us onto another problem, actuance. We are fantastic at resolving detail due to the sharp step in luminosity, this allows us to recognise edges and therefore shapes. (Colour is a different thing, hence why camouflage works so well!) This is why 'unsharp mask' works so well and why your noise ninja artifacts have become problematical. However, (and I apologise for the length of this Rob), we can utilise these idiosyncrasies to our advantage.

In my recent black and white work, I discovered making the blacks more blue/black, seemed to increase the contrast. (RGB 0,0,0 to 0,3,6 and 3,6,9). I can only assume that our eyes poor response to the blue spectrum makes it seem this way. The colour variation has to be very subtle though, (use the shadows option in colour adjustment layers), and works with colour pictures just as well. (I also use a slight red increase and blue reduction in the highlights ensuring no clipping occurs to make an apparent dynamic increase, but this depends on the image contents and colours.)

Actuance is another problem and requires restricted/limited use of unsharp masking, but can be 'confused' by adding more detail. Texture fascinates us, up to a limit, so we notice artifacts less readily. (Try looking at an image with the sky full of cirrus cloud, as compared to a blank blue sky - transitions and noise are less apparent.)
It can also though cause conflictions, ('Where's Wally?' enjoyable or annoying??)

Sorry to have gone on a bit, but it's something that I've found plays some importance to photography. The people looking at photos for acceptance to a submission probably do that all day long, and more and likely become 'numbed' to it all. That's why 'technical consideration' becomes more important to them so anything out of the ordinary 'sticks out like a sore thumb'. We often land up doing that ourselves and over self-criticise.
As I have tried to point out though 'seeing' involves a lot more. I've seen technically perfect pictures that bore me and technically poor pictures that have me transfixed. I've also discovered simple 'tricks' that can transform an image in both capture and post-process.

I really hope this helps somewhat Rob and I'd be more than glad to discuss this further with you. (Just realised how long this is, hope your eyes don't suffer for it!!)

All the Best,
Victor

November 1, 2008 | Unregistered CommenterVictor

Hi Victor,

Great informative reply, makes me really think about how our eyes see photographs, and the unconscious conditioning that is hard-wired into our visual processes.

The process of creating stock photographs is a learning experience for me - a way to build discipline and structure into my image capturing work-flow and routine.

I liken it to the changes I made after using a film camera for the first time. Whereas before I snapped away taking too many shots, now, after using film, I take a lot more time to consider subject, alignment, composition, exposure and framing, and hence I take fewer photo's, but keep more of them.

If I'm out and about and see a scene that I think is interesting and could be used as stock, I take a lot more time, I try to ensure that I get everything right in-camera, so that I can upload "virgin" files to istock, then use post processing on the ones for Flickr.

An important technical challenge of our camera, the S5700, is that it saves photo's as jpgs, compressing the image, so that if you open, edit, and save again, the quality of the image will always suffer.

I've found that in Photography (and life in general) that it's often worth trying to achieve something that's a challenge, even if that's not your final goal, because the skills you learn along the way will benefit the other things you really want to do.

Helpful as ever Victor, keep the comments coming,

Cheers, Rob.

November 1, 2008 | Unregistered CommenterRob_Nunn

Hi Rob,
Sorry the previous post was a bit long, I had a million things in my head and trying to convey them was a bit difficult in the least.
You've learned a hell of a lot on your photographic journey so far and I do really commend you on sharing the things you find.

I've spent years with photography, desperately trying to get it 'right'. 35mm, medium and large format, darkrooms, exhibitions, weddings, corporate events, small triumphs but never a career. The only regret I have is the 'solitude' it imposed. I spent more years buried in darkrooms and stuck behind a camera trying to 'capture' life, that I realised I was merely an observer and not a participant.
Luckily digital has given a new lease of life, fulfilling my emphatic addiction to photography whilst allowing me to participate in the world around me. I can process digital images in a moment compared to my film techniques, I may be in front of a computer, but it is in the house with my family and not locked in a darkroom.

I'm not going to try to 'teach my grandma to suck eggs', you already know the importance of rubbish in - rubbish out, rule of thirds, exposure readings etc. etc.

Our discoveries are 'new-world' adventures and we happily plant our flag, often without seeing the flag planted further up the beach.

Thankyou for all the help you have offered freely and I wish you the very best on your continued journey.

Kindest Regards,
Victor

November 2, 2008 | Unregistered CommenterVictor

Hi Victor,

Don't worry about teaching me to suck eggs - point out every mistake, wrong turn and misunderstanding, I really appreciate your input and wisdom, it keeps me thinking and trying to understand what I'm doing!

You're right about the flag thing, I guess these things have been covered before, but I find the best way for me to learn something is to do it!

Thanks again, and feel free to send me any articles you want to write for the site!

Cheers, Rob.

November 2, 2008 | Unregistered CommenterRob_Nunn

My apologies, the flag reference was in fact regarding my input.

(Conversation is so much easier with additional non-verbal communication and opportunities for reiteration.)

November 2, 2008 | Unregistered CommenterVictor

No apology needed Victor - I value your input and advice!

Cheers, Rob.

November 2, 2008 | Unregistered CommenterRob_Nunn

I am a long time exclusive contributor to istockphoto. On many occasions I have had an image accepted, then resubmitted the image with just minor changes that improved the original, things I should have noticed the first time. But on the second submission I get the "artifacts" story. Now I do everything right, shooting in RAW and never converting to JPEG until the very last step. The the second submission of the image has exactly the same artifacting in as the original submission, yet the second one is rejected. There is an easy conclusion; the rejections for artifacting are not objective or scientific; they are subjective opinions, and are in fact wrong much of the time. Judges are human and they make mistakes, contrary to what istock may want us to think.

February 27, 2010 | Unregistered CommenterJim

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