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Best Way to Resample to Enlarge Image from Severe Cropping

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I find that sometimes I either have to take a picture quickly or I will lose the subject and/or I take a picture then find a picture in a picture. In any case, I get into severe cropping to get the image I want.

In the attached image, the original ORF photo was 4032 x 3024. The cropped version is 1356 x 1077. One web site I use says the cropped version should not be printed larger than 8 x 10". I just used LightRoom Classic to print it out on 11 x 14" paper and it looks good. That implies that LR did a good job of resampling to enlarge it.

I come across this enlarging need frequently and was wondering if there are other good tools to use. 

Thanks

20160301_112137-External.jpg

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gigapixel and photoshop both allow you to enlarge your photos without loosing resolution. 

 

 

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Thanks kdgonzalez. A very useful video. I think one point that may have effected this is how much auto sharpening Topaz does which may have given it a edge.

What it give me a sense of is the relation of PPI loss which I need to look into more.

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I just found this useful article that shows how to get LR to tell you the PPI it will be using. 

In the image above, I had 'Print Resolution' checked and set to 300 ppi. If I uncheck 'Print Resolution', it shows it would print at 103 ppi. So by using 300 ppi, LR will resampling. 

Also found some useful details in this Adobe article on print resolution.

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any sort of bicubic re-sampling will give the best results.  There are limits of course, you can't make up new information - the resolution doesn't actually go up it just does the enlargement and minimizes any artifacts created in the process.  300 DPI is the ideal resolution - you can often get away with 150 DPI or a little lower depending on the image. 

A key thing to do is make sure lightroom or photoshop does all the changes to the image and manages color, that way you have a better chance of previewing your results before printing.  Even your checking of print resolution may not be the best result as it is just using the default re-sampling  far better to have a file resampled to final pixel dimensions which you can preview.  If for example you sharpen your image and check print resolution and LR does this in the background it probably does not apply sharpening on the way to the printer.  If you resample you should always sharpen after you have done that.  Sharpening should always be your last step in the process.

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9 hours ago, ChrisRoss said:

300 DPI is the ideal resolution - you can often get away with 150 DPI

Thanks. I now need to understand PPI to DPI.

 

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PPI=DPI Pixels per inch or dots per inch, it's the same thing.

 

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7 minutes ago, ChrisRoss said:

PPI=DPI Pixels per inch or dots per inch, it's the same thing.

 

I don't believe they are the same. Google DPI vs PPI.

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OK I googled it I had forgotten all about the dots the printer produces.  This issue can be confusing; sure you can change the PPI on a digital image but it really does not change anything unless you resample the image to change the number of pixels.  When looking at an image on screen the only thing that matters is the number of pixels.  Particularly so when viewing in a browser where you want to resample your image so that it is the right size when viewed at 100% - this avoids the browser resampling the image to fit it in the space that is allocated to it.

But when you go to make a print the PPI becomes important.  The correct way to do this is decide on your print size, enter that into the dialog box, set the PPI to 300 then resample the image.  This changes the number of pixels so that the printed image will be 300 PPI when printed at full size.  You then sharpen the image  viewing it at 50 and 100% to judge on screen the sharpening applied.  You can also just resize, but that just changes the PPI and the image doesn't change when viewed on screen as it has the same number of pixels - if you print it - it will change the size of the image on paper though.

Printers have various DPI settings but you really don't interact directly with them the rules of thumb I have heard are to feed a 300PPI image to a Canon Printer and a 360 PPI image to an Epson printer.  You only alter the printer DPI by changing the quality setting in the printer driver and for the best work this is mostly set to it's highest setting or the recommended setting for the paper type you are using - I never even really think about it when printing once you have setup the recommended settings when entering a new paper type into the driver.   The resolution is still effectively the PPI setting, the finer DPI setting is used by the printer to produce a smooth gradation between the larger pixels coming from your image file.

 

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We have done a lot of testing of prints at various resolutions. In our hands, both Canon and Epson printers have their "best" printing at 360 DPI. We tried from 150 - 720 DPI. After 360 not so much improvement, but big differences from 150 to 360. Even 300 to 360 was noticeable but after 360 not much improvement. Of course it depends on both the photo and the paper you are choosing, but for underwater scenes on Red River metallic papers those were the results.

Bill

 

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