LesR
member
Reged: 25/10/2006
Posts: 139
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Now down to some serious work. 
Looking through my shots of the weekend away, I wanted some for mod four. Looking at the histograms I found many with the hill type shape with the tones gently falling away to the sides but then noticed that the final tones - 0 & 255 had a build up of values. As if the pixels had rolled of the hill and landed at the wall of the graph, and as there was nowhere to go just piled on top of each other. Thinking this is wrong I re-checked the manual and found the examples on page 23 showed the same thing.
Now, has this happened to others and if so, has your tutor commented on it in a negative or positive way.
Please help 
Les
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http://www.flickr.com/photos/les_r/
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Terrywoodenpic
A whiff of silicon...
Reged: 21/01/2006
Posts: 920
Loc: Saddleworth UK
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Sorry to but in as I have nothing to do with the course.
What you describe shows typical strong shadows and highlights and probably clipping of both.
Click on the white arrow marker in levels and press alt, and you will see any clipped highlights. do the same with the black one and you will see any clipped shadows.
If none are shown as clipped, you just have a shot with lots of bright highlights and deep shadows with the mid tones more normal.
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65 happy photo years from amateur to professional and back. Caught the bug Young.
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lisadb
Pooh-Bah
Reged: 05/09/2006
Posts: 2269
Loc: Staffs
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Getting pixel pile up, especially on the right hand end, is what you should be avoiding Les, as that means you've got not detail in the brightest areas in the picture. Yes, everyone gets it but when taking the pics check the histogram on your camera regularly so that you can alter the exposure as necessary.
Looking at my own stuff, module 4 is about curves, so I'm a bit confused as to what you're asking. Can you explain a bit further?
I'm off to the Lake District tomorrow for the week, but I'm sure the others will try and help.
PS I shouldn't use pics for mod 4 where the black or white tones have been clipped ie the histogram is piling up at each end, as I think mod 3 was about learning how to avoid this. Have another go for some autumn pics round Clumber Park and keep an eye on your histogram.
 Lisa.
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wollemi - 'look around you, keep your eyes open and watch out' (Australian aboriginal word)
........ Flickr ........ greenglass
Edited by lisadb (26/10/2008 22:47)
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LesR
member
Reged: 25/10/2006
Posts: 139
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Hi Lisa,
If you look at the images numbered 03-02, 04-01, 04-03, for example from our supplied images for the course you can see what I mean.
Some of these are, we are told "have been corrected for levels" but they still show this affect that I am talking about where the last value i.e. 0 and/or 255 has a small stack of pixels even when the general histogram gives the indication that the value should be lower. I'm also thinking it may have something to do with bit depth ?
Les
PS have a good holiday
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http://www.flickr.com/photos/les_r/
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LesR
member
Reged: 25/10/2006
Posts: 139
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Forgot to say why this question arose.
As Lisa rightly said about not having any clipped images for the course.
My workflow for vetting images for the modules goes as follows:
1) check histogram for clipping - if any discard for course and file.
2) check image for content - quality etc
This last batch had a few (that I liked) with what I would call a fair histogram but on closer examination had this small stack of pixels on the outer most tones ( 0 & or 255), that at first just looked like a thicker line.
They were discarded but on checking the histogram on page 23 had the same line and was called " correct".
Also on page 25 the histogram I would not use for the course as it looks clipped on the black tones, has in fact been called " perfect ". So I wanted to know how much clipping is clipping and therefore no good to use for the course and how much is allowable so can be used.
Les
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http://www.flickr.com/photos/les_r/
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