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Old Dec 31, 2009, 9:45 PM   #11
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Which part are you referring to?
In the 100 percent crop of the first image, nothing, not the face or the bricks are in focus. Or perhaps the problem is camera shake?

You make a good point with this thread, but I can spot most P&S camera by their noise reduction software, which tend to have a pastel effect; something not seen on even the worst of the dslr's. This shows up even on reduced size images. Almost all of the 8 meg or larger digicams give themselves away, just on this basis.

Of course some P&S cameras are better than others...

Dave

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Old Dec 31, 2009, 10:04 PM   #12
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Hi Dave, that is exactly the point of the post, to highlight that a photos can be totally out of focus yes after resizing can look pretty OK and not until a 100% crop is used is it possible to see what quality levels we are talking about.

I made this thread as we quite regularly have members post a sample photo that is meant to show quality but as it is a resizded photo there is no possible way to determine how good something really is.
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Old Jan 1, 2010, 12:15 PM   #13
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Hi Dave, that is exactly the point of the post, to highlight that a photos can be totally out of focus yes after resizing can look pretty OK and not until a 100% crop is used is it possible to see what quality levels we are talking about.

I made this thread as we quite regularly have members post a sample photo that is meant to show quality but as it is a resizded photo there is no possible way to determine how good something really is.
As a professional "pendant" I simply can't let anything slide...

If you look at the thread I started in the Sigma forum, I provide not only 100 percent crops, but 200 percent crops...

But the 100 percent crops are pretty useless without the context provided by showing the entire image, as well as the crop. On the "Bird Forum" posters often show their shots of wildlife with reduced size images; I play a game with myself to guess if the image is from a dSLR or a P&S. I am right about 95 percent of the time with these guesses.

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Old Jan 1, 2010, 12:31 PM   #14
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...guess if the image is from a dSLR or a P&S. I am right about 95 percent of the time with these guesses.
And so you would, as anybodys elses guess - because not many photographers would shoot wildlife / birds with a p&s anyway. You can make that 100%


Hey Chato! Long time no see!
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Old Jan 1, 2010, 10:55 PM   #15
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And so you would, as anybodys elses guess - because not many photographers would shoot wildlife / birds with a p&s anyway. You can make that 100%


Hey Chato! Long time no see!
Glad you are back.
Oddly enough Walter, quite a few people use P&S cameras. Just ask Gtoth, who used an Olympus, or for that matter Lyn Evans who has a digiscoping rig with a P&S.

Or, go to the bird forum and peruse their photographs. Indeed, that five percent of the time I am wrong, is probably a damn good guide to which P&S doesn't have heavy NR...

I've been down for six weeks because Earthlink is the most incompetent company I've ever had the bad luck to do business with. Three times that had no record of my asking for a change to address (not that stopped them from billing me.) Moreover when I called to terminate my service, the clown all of a sudden had a record of my requests...

Really, really very strange...

Heck, I wouldn't even inflict these people on Bynx...

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Old Jan 11, 2010, 4:00 AM   #16
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Thanks, Mark, for this excellent thread, which deserves to go somewhere in the 'welcome', when new members join, or as a sticky in all the forums where image quality is a particular issue.

The way I like to put "100% crop" is as "pixel for pixel". If you post an image that's 800x600 pixels, and your web browser says it's giving a 'Zoom level' of 100%, one pixel on your monitor corresponds to one pixel of the posted image.

The one point I'd like to add is that for comparison of images the viewing conditions need to be standardised as well. I'm sitting now at my own monitor with a diagonal of 440mm with my eyeballs about 680mm from the screen (1.54x) If I walk along to my son's 470mm monitor my eyes are 810mm (1.72x diagonal as far away). If I view an image on mother-in-law's giant HD TV, sitting at the other end of a long room, it's different again.

'100% crops' on the same screen viewed from the same distance, preferably with images side-by side, is the way to do comparisons.

As for "200% crops" from the original, where each pixel of the original is spread over four pixels on the monitor instead of one, I imagine that it might mean that comparisons would be less dependent than "100%" on how well the monitor displays any individual pixel. Perhaps some electronically qualified optician/optometrist would like to comment? Would monitor dot pitch differences have any effect?

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Old Jan 11, 2010, 5:34 PM   #17
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Thanks, Mark, for this excellent thread, which deserves to go somewhere in the 'welcome', when new members join, or as a sticky in all the forums where image quality is a particular issue.

The way I like to put "100% crop" is as "pixel for pixel". If you post an image that's 800x600 pixels, and your web browser says it's giving a 'Zoom level' of 100%, one pixel on your monitor corresponds to one pixel of the posted image.
Yes and no.

If such were the case, you would be able to actually see the individual pixels; something that doesn't occur until you get about a 600 percent zoom. This is because your monitor does NOT actually show pixels. Take a strong magnifying glass, and you will see that your monitor is fooling the eye into seeing the image. Your monitor actually is composed to individual dots of R, G and B (along with "empty dots" of white and black - i.e. no RGB or all RGB) which fool the human eye into seeing the color spectrum

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The one point I'd like to add is that for comparison of images the viewing conditions need to be standardised as well. I'm sitting now at my own monitor with a diagonal of 440mm with my eyeballs about 680mm from the screen (1.54x) If I walk along to my son's 470mm monitor my eyes are 810mm (1.72x diagonal as far away). If I view an image on mother-in-law's giant HD TV, sitting at the other end of a long room, it's different again.

'100% crops' on the same screen viewed from the same distance, preferably with images side-by side, is the way to do comparisons.

As for "200% crops" from the original, where each pixel of the original is spread over four pixels on the monitor instead of one, I imagine that it might mean that comparisons would be less dependent than "100%" on how well the monitor displays any individual pixel. Perhaps some electronically qualified optician/optometrist would like to comment? Would monitor dot pitch differences have any effect?

Have fun
Alan T
I believe that correctly color calibrating your monitor is far more important than the size of the display. Whatever the size, we are not actually seeing pixels, we are seeing itty, bitty dots of color...

Here's a 300 percent crop from my little Sigma...



In the above we are seeing a different method of capturing pictures than the typical Bayer pattern chip.

All of the above being said, I am certainly ready to be corrected, since this is not a field in which I make a claim to expertise.

Dave
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Old Jan 11, 2010, 6:36 PM   #18
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Actually, when you use the monitor's recommended resolution, it uses three of those itty, bitty dots of color, one red, one green, and one blue, to represent a single pixel. The number of itty, bitty dots on a monitor is fixed, so if you use some resolution other than that recommended by the manufacturer, then the pixel representation is inexact, but if you do, then it's sharp.
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Old Jan 12, 2010, 5:35 PM   #19
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Actually, when you use the monitor's recommended resolution, it uses three of those itty, bitty dots of color, one red, one green, and one blue, to represent a single pixel. The number of itty, bitty dots on a monitor is fixed, so if you use some resolution other than that recommended by the manufacturer, then the pixel representation is inexact, but if you do, then it's sharp.
Well, yes, this is true, but you cannot see the individual pixels of the image at 100 percent. Which is just peachy, because otherwise you would be looking at little squares...

You can even view the individual dots with a strong magnifying glass.

But this is besides the point.

Different individuals with different monitors (no matter what the resolution) to be able to compare images, if the monitors are properly color calibrated.

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Old Feb 7, 2010, 11:21 PM   #20
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Default Why a resized photo is no use in showing camera quality

During the discussion in this thread Chato made the comment about a "good guide to which P&S doesn't have heavy NR..." I now have an Olympus SP590 and have recently noticed that if I move to the P, A, S, M modes (and I think some others) I get 'NR' in a rectangle at the top of the monitor or view finder along toward the right hand corner. I have searched the camera manual but can find no reference to this information ....

s o o o o..... what is 'NR'?

Thanks for un-mystifying me.
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