Posted by Steve Balke on August 23, 2010 at 9:11 PM
How large a crop can we make without the size of the crop influencing the quality of our posted image? I’ve been testing the limits in the posts to the avian gallery lately and find that an image can retain very fine detail even when cropped from 18 MP to 1.8 MP! (see the posted hummingbird image) . I prefer to use MP of the cropped image rather than percentage to express cropping because it’s independent of the camera. However, since percentage use is commonplace I’ll note that’s only 10% of the original image! The guideline I’ve often seen here is 50%. If we could routinely make high quality 10% crops it would make a large difference in what images we decide to retain and even what lenses we purchase.
Briefly here are some points that I’ve been thinking about:
• The detail that we see in the image is influenced by several important variables other than the number of MP of the cropped image: the quality of the lens/camera system, the number of pixels actually devoted to the subject (the bird in my case), the scale of detail in the actual subject (size of barbs in the feathers for example), the lighting, camera motion, subject motion, noise level, post-processing effects.
• If we consider only the total MP of the cropped image, and the other variables mentioned above are o.k.., I don’t think that we will see an effect of cropping so long as the length of the cropped image before posting is greater than the 1200 pixels on the longest side. If we are printing the image, of course, that is another matter. Then we need to allow for 200 to 300 pixels per inch of printed image. However, even then we now have some pretty powerful uprezzing software to help us for larger prints.
So, my conclusion, tentative at this time since I’m still trying to sort this out, is as follows:
Don’t worry about the size of the cropped image so long as it exceeds 1200 pixels on a side. Just consider the appearance of the image on it’s own merits. If it looks good to you, post it. If there is an image quality problem, look to causes other than the size of the cropped image. Quoting the crop size as total MP of the cropped image is still useful because it relates to the possible need for an uprezzing program for printing.
Please especially let me know if you think I've missed something here. Also, note that this situation is changing (i.e. improving!) rapidly: new cameras, software, etc.
Perhaps some of you have examples of large crops that show fine image quality despite the crop, that you would like to post here?
Posted by Richard Ditch on August 23, 2010 at 11:54 PM
If all you are trying to do is have a web post that looks good, then I agree with most of what you say. I disagree about being able to up-res an image from a small (e.g.1.8MP image) to something that has the detail of a large image that didn't have to up-res'd to get that big. No matter how advanced the software is it can't invent fine detail for the up-res'd image.
If you rely on large crops (low MP files) you are limiting yourself to web posts. If you build a web site on this basis and don't make that limitation obvious how will you explain to a commercial buyer who wants to buy your image for a book or magazine?
You've also ignored the issue of noise: by working with a severely cropped file you are in essence magnifying the image noise along with the detail you've retained. I can see that noise in this image, and it has been made more obvious by the amount of sharpening required to make the remaining detail look ok.
Maybe it's just me, but I am looking at the bird and not the noise in the image. I only wish I had an image of a hummingbird that looks this great
Troup
Posted by Mia McPherson on August 24, 2010 at 6:33 AM
Steve,
The image I have attached is 5% of the original frame. Detail is ok, sharpness is ok, noise level is ok. For posting on the web it looks ok, for publishing in a magazine, not so ok.
The large crop would make it impossible for me or a publisher to print this and expect fine quality. There is some loss of detail visible to me due to the large crop and it doesn't quite meet my personal standards.
I agree with Rich in that up-rez software can not invent fine detail.
I use percentage of crop regardless of whether I am using my D200 (10.0 mp) or my D70 (6.0 mp) because it is based on what percentage I am actually using from the original image.
Posted by Lance Warley on August 24, 2010 at 7:37 AM
I'm with Troup.
That hummer shot is stunning. Crop-schmop.The colors and details are amazing.
A real beauty.
Posted by Hali Sowle on August 24, 2010 at 9:25 AM
I guess it is all in what you want to do with the image - if you just want them for a web gallery that's fine but if you want to print them or sell the rights for commercial use then as gorgeous as the image is it's not viable for that.
But there is no doubt that that is a gorgeous hummingbird shot (and the juvenile skimmer is fantastic too)
Posted by Steve Balke on August 24, 2010 at 11:30 AM
Interesting and enjoyable comments. Thank you all. A special thanks to Mia for posting that beautiful image. I thought I should interject another comment, even so soon after posting, because I can see that one main thrust of the response is: good for web, not good for commercial publication. My understanding is that at most a publisher requires 300 pixels per inch of printed image (is that correct?). If so, then even the little 1.8 MP hummingbird image (1325 pixels by 1325 pixels) could be printed as a 4.4 inch by 4.4 inch image without use of any uprezzing software.
In general, by this reasoning, if we want to allow a publisher the option of printing our image at 8 inch by 10 inch size without uprezzing then we need an image 2400 pixels x 3000 pixels or 7.2 MP. That's a 40% crop for the 18 MP of the 7D. Of course, if the publisher can live with less than 300 pixels per inch or is willing to use one of the uprezzing programs the percentage becomes larger.
Perhaps there are other considerations though beyond the image appearing of high quality and being of a small MP size. I hope that any of you who have discussed this with publishers will also comment.
Posted by Richard Ditch on August 24, 2010 at 12:01 PM
My experience with publishers is that they often want the full frame uncropped image so that they can decide how to crop the image for their use. If you have already tossed out most of the frame they are forced to use your image with the framing you have provided and that might mean the image will not work for them.
Since I'm posting a second time I figured I might as well toss in this image - it is 18% of the full 10MP D200 image. I talked about it in this post on my blog where I also show the full frame version.
Posted by Richard Ditch on August 24, 2010 at 1:03 PM
Just to expand on my point about publishers wanting to do their own cropping from full sized images, here's a puzzle form Springbok that uses 9 of my bird photos. The publisher selected the images, I supplied the full frame high res files, and then the publisher cropped for the final layout.
Here's a link to the puzzle which is also available in HallMark stores and at Amazon.com among other sources.
Posted by Steve Balke on August 24, 2010 at 10:36 PM
Thank you, Richard. Outstanding work. Beautiful images and an example of commercial success too! It certainly makes sense that publishers would prefer to do their own cropping from a full size image. Of course, that doesn't stop us from posting our own crop and supplying the publisher with the original uncropped image. With regards to this discussion topic your posts make me think of two major points:
i. For that lovely close-up of the wigeon you say in your blog that the detail we see is an illusion. I think what you are referring to is that if the image was larger in pixel size then more pixels would be representing each detail of the bird. However, I think the point is that maybe we don't need more pixels in this case. Possibly less detail is visible in such a small image. However, there is so much detail that is present that we don't miss it. The image still comes across as a high quality, beautiful, publishable image.
ii. For the bird puzzle images the question that arises is what crop the publisher used for each image to produce the puzzle images. Would the publisher have been satisfied with ending up with a 2 MP image for each of the birds in the puzzle for example?
Posted by Richard Ditch on August 25, 2010 at 12:05 AM
Steve:
All but the sapsucker should be on my web site if you want to see the original versions I submitted. The species are as follows:
The sapsucker is an old film shot that I tried to discourage the editor from using but he insisted.
Here's the relevant instruction I had for supplying the images: "I will need the images as large as the file or your camera will allow. The finished puzzle will be approx. 20” x 20” with the individual square bird images being about 6” square after we crop in tight on the bird."
I think the tight crop on the American Wigeon works with so few pixels because the bold pattern distracts the viewer from the lack of fine detail in the feathers that should be in a shot this tight. If I could have been close enough to get this full frame instead of as a major crop then I would expect to see a lot more feather texture in the white areas on the face and in the browns on the back.
Posted by Steve Balke on August 25, 2010 at 11:13 AM
Thank you again, for your very helpful input, Rich. Your publisher sounds pretty flexible to me: while wanting as many pixels as possible the final crop is 6 inches square (1800 pixels square for a total of 3.2 MP) for each bird image. Also, even a scanned film print that you were not happy with is o.k. since it fit the requirement.
The three postings here (yours, Mia's and mine) have demonstrated that it is possible to obtain a good looking image that is only a few MP in size. We can have different explanations as to why an image looks good at that size. However, the main point is that high crop (low percentage) does not necessarily mean a poor quality image.
Whether it is enough to satisfy most publishers is uncertain. From what I know at this point, I figure that if it is high quality enough to satisfy me, I'll post it and find out what other photographers think of the quality, no matter what the crop, so long as it is larger than 1200 pixels on the longest side.
Discussion
11 repliesBriefly here are some points that I’ve been thinking about:
• The detail that we see in the image is influenced by several important variables other than the number of MP of the cropped image: the quality of the lens/camera system, the number of pixels actually devoted to the subject (the bird in my case), the scale of detail in the actual subject (size of barbs in the feathers for example), the lighting, camera motion, subject motion, noise level, post-processing effects.
• If we consider only the total MP of the cropped image, and the other variables mentioned above are o.k.., I don’t think that we will see an effect of cropping so long as the length of the cropped image before posting is greater than the 1200 pixels on the longest side. If we are printing the image, of course, that is another matter. Then we need to allow for 200 to 300 pixels per inch of printed image. However, even then we now have some pretty powerful uprezzing software to help us for larger prints.
So, my conclusion, tentative at this time since I’m still trying to sort this out, is as follows:
Don’t worry about the size of the cropped image so long as it exceeds 1200 pixels on a side. Just consider the appearance of the image on it’s own merits. If it looks good to you, post it. If there is an image quality problem, look to causes other than the size of the cropped image. Quoting the crop size as total MP of the cropped image is still useful because it relates to the possible need for an uprezzing program for printing.
Please especially let me know if you think I've missed something here. Also, note that this situation is changing (i.e. improving!) rapidly: new cameras, software, etc.
Perhaps some of you have examples of large crops that show fine image quality despite the crop, that you would like to post here?
If you rely on large crops (low MP files) you are limiting yourself to web posts. If you build a web site on this basis and don't make that limitation obvious how will you explain to a commercial buyer who wants to buy your image for a book or magazine?
You've also ignored the issue of noise: by working with a severely cropped file you are in essence magnifying the image noise along with the detail you've retained. I can see that noise in this image, and it has been made more obvious by the amount of sharpening required to make the remaining detail look ok.
Troup
The image I have attached is 5% of the original frame. Detail is ok, sharpness is ok, noise level is ok. For posting on the web it looks ok, for publishing in a magazine, not so ok.
The large crop would make it impossible for me or a publisher to print this and expect fine quality. There is some loss of detail visible to me due to the large crop and it doesn't quite meet my personal standards.
I agree with Rich in that up-rez software can not invent fine detail.
I use percentage of crop regardless of whether I am using my D200 (10.0 mp) or my D70 (6.0 mp) because it is based on what percentage I am actually using from the original image.
That hummer shot is stunning. Crop-schmop.The colors and details are amazing.
A real beauty.
But there is no doubt that that is a gorgeous hummingbird shot (and the juvenile skimmer is fantastic too)
In general, by this reasoning, if we want to allow a publisher the option of printing our image at 8 inch by 10 inch size without uprezzing then we need an image 2400 pixels x 3000 pixels or 7.2 MP. That's a 40% crop for the 18 MP of the 7D. Of course, if the publisher can live with less than 300 pixels per inch or is willing to use one of the uprezzing programs the percentage becomes larger.
Perhaps there are other considerations though beyond the image appearing of high quality and being of a small MP size. I hope that any of you who have discussed this with publishers will also comment.
Since I'm posting a second time I figured I might as well toss in this image - it is 18% of the full 10MP D200 image. I talked about it in this post on my blog where I also show the full frame version.
Here's a link to the puzzle which is also available in HallMark stores and at Amazon.com among other sources.
i. For that lovely close-up of the wigeon you say in your blog that the detail we see is an illusion. I think what you are referring to is that if the image was larger in pixel size then more pixels would be representing each detail of the bird. However, I think the point is that maybe we don't need more pixels in this case. Possibly less detail is visible in such a small image. However, there is so much detail that is present that we don't miss it. The image still comes across as a high quality, beautiful, publishable image.
ii. For the bird puzzle images the question that arises is what crop the publisher used for each image to produce the puzzle images. Would the publisher have been satisfied with ending up with a 2 MP image for each of the birds in the puzzle for example?
All but the sapsucker should be on my web site if you want to see the original versions I submitted. The species are as follows:
Streak-backed Oriole, Yellow-breasted Chat, Lawrence's Goldfinch
Northern Parula, Peach-faced Lovebirds, Red-naped Sapsucker
Northern Cardinal, Wilson's Warbler, White-winged Dove
The sapsucker is an old film shot that I tried to discourage the editor from using but he insisted.
Here's the relevant instruction I had for supplying the images: "I will need the images as large as the file or your camera will allow. The finished puzzle will be approx. 20” x 20” with the individual square bird images being about 6” square after we crop in tight on the bird."
I think the tight crop on the American Wigeon works with so few pixels because the bold pattern distracts the viewer from the lack of fine detail in the feathers that should be in a shot this tight. If I could have been close enough to get this full frame instead of as a major crop then I would expect to see a lot more feather texture in the white areas on the face and in the browns on the back.
The three postings here (yours, Mia's and mine) have demonstrated that it is possible to obtain a good looking image that is only a few MP in size. We can have different explanations as to why an image looks good at that size. However, the main point is that high crop (low percentage) does not necessarily mean a poor quality image.
Whether it is enough to satisfy most publishers is uncertain. From what I know at this point, I figure that if it is high quality enough to satisfy me, I'll post it and find out what other photographers think of the quality, no matter what the crop, so long as it is larger than 1200 pixels on the longest side.