Why the quality loss?
Feb 1, 2018 17:42:04 #
My camera is a 24 megapixel camera, takes photos about 20" x 13.33." I have heard, and read, that when you crop a photo, you lose image quality, and I cannot understand why! If I want to print my photo at, say an 8" x 10," and I crop the photo to 8" x 10" size, I know I am losing pixels, but how does that reduce image quality? The pixels I lost will be on the fringes of the photo, and not the main part of the photo itself. I can see, perhaps, if I crop and still want to print a 20' x 13" photo, image quality might be compromised, but I just don't understand image quality loss in the example I gave. Please, no demeaning comments, I realize I am not the sharpest tack in the box, that is why I reach out to the sharpest tack(s)!
Feb 1, 2018 17:44:18 #
Cropping a photo only loses IQ if you crop too much for the size print you need. What is still there is the same quality as it was when there were more pixels beyond it.
Feb 1, 2018 17:47:44 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
When you (ratio) crop you do not lose quality. If you reduce the image you to fit a print size you lose a ton of data.
When you crop to a ratio, it not the same thing as cropping for 'isolation', meaning to cut the part of an image in order to see only that.
Even then you do not lose anything. You will lose when you print, project or view to a higher size than the (isolated) cropped area, you have fewer pixels to exploit.
Feb 1, 2018 17:49:03 #
I think your conclusions are correct. When you crop you. Lose pixels; and to maintain the same quality you can no longer print the photo to the same size you previously could. But the new smaller size may be perfectly acceptable.
Feb 1, 2018 17:56:41 #
Any time you crop, you lose pixels and resolution. Now whether that’s a visible difference on the size print or image you ultimately output is a different question.
Feb 1, 2018 18:22:11 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
Assuming your 24mp image is originally 6000 x 4000 pixels and you "crop" an area of that image to 2400 x 3000 pixels you will be able to print your 8x10 at the same 300 ppi as your 20x13.33 un-cropped image. There would be no quality loss in this example.
You can begin to lose image quality when you re-size and "re-sample" an image, or when it would require a lower resolution to print at the desired size.
Feb 1, 2018 18:31:54 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
You are zooming into an image the resulting lack in quality is because, think of it as, to closer you get the bigger the pixels get. A 56 Mb image from a Nikon D850 has a lot room to crop, because you have a bigger starting point.
Feb 1, 2018 18:49:20 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
The discussions are confused and imprecise to begin with. If you are talking about JPGs that you keep working with instead of as final output you will have problems. Your camera output is in a 2:3 ratio format. Say you have a 10x15" image in Ps as a TIF file, just Save As a New File with different name for each and any crop you want to make and you should loose nothing from the actual image area of a "print", as long as you start with the original each time. Where you will loose resolution and pixels is if you go from a cropped 8x10 and try to scale up and recrop it as a 10x15 you will actually have lost two inches from the 8" side. I usually try to work with full frames 10x15, 8x12 and only crop to remove edge junk I don't want and not for creating convenient print sizes. Sure I might crop to some standard size if the image warrants it. This stuff is easier to see ad do than to explain. It can also be more problematic with Lr as you are not normally creating more and more files all the time.
Feb 1, 2018 18:53:42 #
Rick36203 wrote:
Assuming your 24mp image is originally 6000 x 4000 pixels and you "crop" an area of that image to 2400 x 3000 pixels you will be able to print your 8x10 at the same 300 ppi as your 20x13.33 un-cropped image. There would be no quality loss in this example.
You can begin to lose image quality when you re-size and "re-sample" an image, or when it would require a lower resolution to print at the desired size.
You can begin to lose image quality when you re-size and "re-sample" an image, or when it would require a lower resolution to print at the desired size.
Make sure you're working with the mentioned 2400X3000 or equivalent depending on your originals pixel count and you will be fine. If your crop results in a smaller pixel count and you then print at 8X10, yes it will fall apart.
Feb 1, 2018 19:53:50 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
If you can still print at 300 dpi you should be ok...
A long time a go someone figured out the naked eye could just about resolve 5 line pairs per mm at a normal viewing distance. thats 10lines per mm or 254 per inch when apple designed the retina display they made it 264 pixels per inch and said you can't see the pixels. Printers figured 300 dpi was enough resolution for a photo at normal viewing distance.
You might want a little bit more, say there is a little purple or green or red fringing which will not be easy to see if you have plenty of pixels per inch but may be rather obvious at 300dpi although to be fair it would be visible on a 20" print as well.
If you can think of a threshold where below a certain size defects and pixels can't be resolved the more you crop and the more you enlarge the greater the chances of these defects actually being visible in the final print.
Feb 2, 2018 06:45:00 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
Look at your image at full size on the computer screen, then magnify it to 2:1 or 3:1 - do you see the loss in quality? It's no different when you print. You nailed it when you said you understand you are using fewer pixels when you crop. Fewer pixels = lower image quality. if you have something in the image that is 50 pixels wide, but is only 1/4" on the uncropped image, then you crop it so that the 50 pixels is now 10" wide, it doesn't matter whether the part that you cropped away was at the edge or the center. You are still magnifying something that is 1/4" to 10" and using only 50 pixels to do it. Of course there will be a loss in image quality.
Feb 2, 2018 06:53:40 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
If you do extreme cropping of an image there will be an apparent loss of quality because you will start being conscious of individual pixels. It is like taking a magnifying glass and looking at just a tiny part of the image. There is no real loss of quality, but it seems like it.
With less cropping you may not be conscious of the individual pixels but you still perceive the image as not being quite as good, perhaps a bit blurred.
Feb 2, 2018 07:23:49 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
You lose quality because when viewing or printing an image, the cropped version is magnified compared to the original, assuming both versions are viewed or printed at the same size. Although the loss may not be noticeable depending on the amount cropped or size of the print (view).
Unless you take it to extremes or start with a very small image its probably not worth being concerned about.
Feb 2, 2018 08:15:01 #
jradose wrote:
My camera is a 24 megapixel camera, takes photos a... (show quote)
What cropping does is enlarge the image, so any defects - noise, focus, exposure - become more apparent.
Feb 2, 2018 09:38:56 #
"Cropping a photo only loses IQ if you crop too much for the size print you need. What is still there is the same quality as it was when there were more pixels beyond it."
In total agreement.
In total agreement.
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