100% Crop

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Dave
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Hi all,

Sorry for the probably silly question. I am new to photgraphy and I keep seeing the following when people are demonstrating the IQ of a lens "100% crop".

What does "100% Crop" actually mean? :thinking:

Thanks

Dave
 
It's a portion of the image posted without being resized so, rather than crop a section of the image and then resize it to 800px square (for example), you set the image to full size on your screen and then cut out an 800px square portion of it and post that without resizing.
 
It means a crop of the image that is small enough to be displayed on a monitor without shrinking it to fit the screen. e.g. suppose you had an image of 3000x2000 pixels from a 6 megapixel camera and your screen was only 1600x900. You could not view the whole image on the screen without shrinking it. To get a 3000x2000 image displayed on a 1600x900 monitor you'd need to resize it to 45% of the original pixel size. If you wanted to display it on a 1366x768 monitor it would have to be resized to 38% of the original size.

When you shrink it (resize is a better term) you lose some of the detail that was originally captured and you also conceal problems like noise, shake, blur, misfocus etc.. That makes it difficult to determine the true quality of the original image.

To make a 100% crop you crop out an area from the photo that is small enough to be displayed, without being resized, on pretty much any monitor and to comply with forum limits. Thus you would crop out, for example, an area of 800x533 pixels and produce that cut down (not resized) image as 800x533 pixels. That way you show a smaller part of the photo, but show it at 100% of its original size. i.e. each original pixel from the camera is displayed as one pixel on screen. It's a 1:1 ratio, or 100%.
 
Ahhh, now I see why it is used a lot when people are asking about lens quality.

Thank you very much! :thumbs:
 
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so is the term "pixel peeping" the same as viewing at 100% or something different,if it's the same why is viewing at 100% not a good idea as I hear people say not to pixel peep?
 
so is the term "pixel peeping" the same as viewing at 100% or something different,if it's the same why is viewing at 100% not a good idea as I hear people say not to pixel peep?


Pixel peeping is examining a digital image down a very fine detail, possibly at the individual pixel or dot on a screen level Because people spending thousands of pounds on lenses want the best possible picture in terms of image quality (IQ) or sharpeness.
 
Pixel peeping is examining a digital image down a very fine detail, possibly at the individual pixel or dot on a screen level Because people spending thousands of pounds on lenses want the best possible picture in terms of image quality (IQ) or sharpeness.

So that they can post the best possible quality 72ppi jpegs on Flickr mostly.
 
So that they can post the best possible quality 72ppi jpegs on Flickr mostly.

:lol: No idea why they do it, but thats not what was asked anyway! :shrug:
 
I was just being sarcastic.
A lot of the time the people looking at 100% crops and doing the really geeky pixel peeping are the ones that end up doing nothing with their images other than posting them on Flickr.
 
so I think I got it now,100% crop is the full size image but we never really print or view the pic that big so 100% viewing is not really needed,pixel peeping is taking it farther and they need OCD medication? cheers wontolla and fixedimage.
 
So that they can post the best possible quality 72ppi jpegs on Flickr mostly.

PPI makes no difference to digital images - ppi is only used to give a finished print size - An 800px x 600px image is the same image whether at 300ppi, 72ppi or 1000ppi........ What would change is only the sze of the physical print. ppi controls only the size of the finished print.
 
So that they can post the best possible quality 72ppi jpegs on Flickr mostly.

PPI makes no difference to digital images - ppi is only used to give a finished print size - An 800px x 600px image is the same image whether saved at 300ppi, 72ppi or 1000ppi........ What would change is only the sze of the physical print. ppi controls only the size of the finished print.
 
....... the ones that end up doing nothing with their images other than posting them on Flickr.

Nothing wrong with that is there if thats what they want to do?

Allan
 
so I think I got it now,100% crop is the full size image but we never really print or view the pic that big so 100% viewing is not really needed,pixel peeping is taking it farther and they need OCD medication? cheers wontolla and fixedimage.

Not necessarily, a 100% crop basically maps the pixels on your monitor 1:1 with the pixels in the image.

If your screen is 1680 x 1080 and you could use all to see the image then the 100% crop you show 1680 x 1050 pixels of your image. If your screen res os 1024 x 768 then your 100% crop would look larger because you only see 1024 x 768 pixels (actually less because pixels are used by the software for windows.

That's why with a higher screen resolution, the same images or icons look smaller.

A 100% crop as mentioned above is a shot of the image at 1:1 pixel level. 1 pixel on the image = 1 pixel on the screen.
 
Pixel peeping is examining a digital image down a very fine detail, possibly at the individual pixel or dot on a screen level Because people spending thousands of pounds on lenses want the best possible picture in terms of image quality (IQ) or sharpeness.

That's part of it, but it also helps to be able to check that the equipment is set up to its best potential and also to look for flaws in technique, in order to identify opportunities to improve.

If all you will ever do is to produce little webshots then perhaps pixel peeping is overkill, but if you are submitting images to a stock library, or wish to print or display on a large scale, or simply take pride in achieving the best result you can then pixel peeping is a legitimate activity. You've paid for all those pixels. You may as well make sure they are doing something useful.

If you are shooting wildlife, for example, and are focal length limited, then you may find yourself needing to crop quite a bit in order to achieve an acceptable composition. The harder you crop the more important it is that your images are pixel perfect. If you have a series of similar shots then examining at the pixel level may help you choose the winner out of the set. Some people actually do use images at 100% as their final product, after cropping. The better you and your gear are then the more success you are likely to have. Pixel peeping can be a learning exercise.

You may also find, with a camera such as the 5D2, which has lots of megapixels each of very high quality, that it is possible to create two or more images from one shot, simply by cropping in different ways. An image that is shot perfectly and looks good at the pixel level will give you that option. A sloppy shot that will just about pass muster on a web forum will not.

Here's an example of a street candid taken with my 5D2 and 50mm lens. I wasn't close enough to make for an interesting shot, so I cropped in software. Maybe you like the end result, maybe not, but with a fairly solid image to begin with at least I had the option.

Original without edits....
20101106_111503_6141_LR.jpg


Cropped and tweaked....
20101106_111503_6141_LR-2.jpg
 
cheers tdodd:thumbs:

so whats the process for pixel peeping,I see on my canon software it can zoom in to each pixel but not sure how that helps,after you go past the point where the pic is no longer looks recognizable?
 
cheers tdodd:thumbs:

so whats the process for pixel peeping,I see on my canon software it can zoom in to each pixel but not sure how that helps,after you go past the point where the pic is no longer looks recognizable?

That's pretty much it, when you get to the stage where a twig on a tree branch that's maybe 1-2 pixels wide is taking up 50% of your screen then you are definitely pixel peeping!

Incidentally that's useful for checking sharpness, as if that same twig has a 1 pixel wide white band around it you knw you've oversharpened or screwed up the focus for that twig...

There is an element who expect to be able to see sharpness from corner to corner on a shot like that at f2, they're the kind who are deluding themselves, and are the kind of folk usually refered to as pixel peepers in a derogatory way.
 
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If you're talking about DPP then you have four zoom levels available - Fit, 50%, 100% and 200%. Because the "Fit" option has to resize to some arbitrary size to fit the screen the resulting image quality is constrained by the success of the resizing algorithm to cram so many megapixels into such a small space. You can't make a good judgement of IQ at such a size.

Viewing at 50% gives the software a much easier time of calculating how to display the image. It is effectively the equivalent of squeezing exactly four pixels from the camera into one pixel on the display. At 100% the software does not need to fiddle about with the pixels at all. what you see displayed is exactly what the camera shot. Viewing at 50% or 100% is a good way to judge image sharpness.

I can't see any value in viewing at 200%. Then the software is taking each single pixel from the camera and displaying it over four pixels on the screen. It has to invent pixels that were never there. I don't view at 200%.

Whether using DPP or Lightroom/Photoshop or something else, you will usually get the best indication of IQ when viewing at a simple integer fraction ratio - 1:1, 1:2, 1:3, 1:4. Viewing at any other ratio is usually not going to reflect the quality of the image as well as it might. Viewing at 1:2 (50%) or 1:3 (33%) is probably the best way to get an idea of how good the picture will look as a large print.
 
Tim
As a note it depends on the version of Photoshop you use as in older versions it was best to look at images at 25%, 50%, 100%. Levels like 33% and 66% were not sampled correctly in older versions.
 
OK. Fair enough. I use Lightroom 3.3. I don't use Photoshop. I assume later versions are OK at 33%.
 
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