Resizing help for best quality

sherbs79

sherbs79

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Scott
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Hello All

Despite numerous YouTube videos I still can't get my head around this. I have been asked to print a 60 x 30 inch canvas of a landscape shot, as it's costing over £120 at the local pro printer I want to make sure it's of the best quality! So my question is, if I resize in LR to 60" x 30" and when exporting keep the PPI at 300 but untick the "resize for" box does this then mean I'm sending the printers a high res file at 60 x 30 so it's of the best quality possible?

This is seriously doing my head in, all the YouTube videos seem to have a different take on it [emoji85]

Thanks
Scott
 
In LR's pop up export menu under image sizing you want 'Resize to Fit' ticked and 'Don't Enlarge' not ticked.

However, this image would be 162 Megapixels!!! And I'm guessing you didn't start with anywhere near that resolution. Now I know DSCL for example go on about requiring 300ppi, but I would strongly recommend you to read up on ppi and the effect viewing distance has on it. Basically 300ppi is required for a sharp detailed 12"x6" print that is going to be viewed very close, but your massive 60"x30" print is going to be viewed from metres away on the other side of a room and the human eye simply can't resolve 300ppi at that distance.

There comes a point where uprezzing, basically adding pixels through a software algorithm, that were not there in the first place does more harm than good. Don;t get me wrong there is some good software out there but before committing to a massive print like that personally I would be cropping a 12"x6' from the final image size out of the image and getting it printed at various PPI's with various amounts of output sharpening on it before ordering the large one. This is achieved by appreciating that 12" compared to 60" is one fifth, so if your original image is 6000pixels wide, crop a 2x1 ratio crop from it at 1200pixels wide, which has a native resolution of 4" at 300ppi, then output it to 12" wide which drops the native resolution to 100ppi. From here you can increase the output resolution, personally I would be looking to end up at a maximum of 180ppi, but the beauty of this test is you can cheaply do one at 100, one at 150, one at 180, one at 240 and one at 300 to identify the best IQ.

Hope this helps.
 
Just how big is the file to start with before you are asking LR to upscale it I.e. what are the pixel dimensions?

Secondly IMO LR or indeed PS are not the best when it comes to big upscalings, so have you spoken to the pro printers because their "drivers"/processing may likely upscale better to suit the canvas and the printer being used...... plus they could advise whether the level of upscaling is appropriate for the file size???
 
Craig_85 said:
In LR's pop up export menu under image sizing you want 'Resize to Fit' ticked and 'Don't Enlarge' not ticked.

However, this image would be 162 Megapixels!!! And I'm guessing you didn't start with anywhere near that resolution. Now I know DSCL for example go on about requiring 300ppi, but I would strongly recommend you to read up on ppi and the effect viewing distance has on it. Basically 300ppi is required for a sharp detailed 12"x6" print that is going to be viewed very close, but your massive 60"x30" print is going to be viewed from metres away on the other side of a room and the human eye simply can't resolve 300ppi at that distance.

There comes a point where uprezzing, basically adding pixels through a software algorithm, that were not there in the first place does more harm than good. Don;t get me wrong there is some good software out there but before committing to a massive print like that personally I would be cropping a 12"x6' from the final image size out of the image and getting it printed at various PPI's with various amounts of output sharpening on it before ordering the large one. This is achieved by appreciating that 12" compared to 60" is one fifth, so if your original image is 6000pixels wide, crop a 2x1 ratio crop from it at 1200pixels wide, which has a native resolution of 4" at 300ppi, then output it to 12" wide which drops the native resolution to 100ppi. From here you can increase the output resolution, personally I would be looking to end up at a maximum of 180ppi, but the beauty of this test is you can cheaply do one at 100, one at 150, one at 180, one at 240 and one at 300 to identify the best IQ.

Hope this helps.
Click to expand...

So is there a chance that at 300PPI the picture won't look great??
 
Box Brownie said:
Just how big is the file to start with before you are asking LR to upscale it I.e. what are the pixel dimensions?

Secondly IMO LR or indeed PS are not the best when it comes to big upscalings, so have you spoken to the pro printers because their "drivers"/processing may likely upscale better to suit the canvas and the printer being used...... plus they could advise whether the level of upscaling is appropriate for the file size???
Click to expand...

The dimensions before I resize are 5984 x 2738 and after resizing it is 5476 x 2738
 
So I've done a quick print to file export using LR and it says it's going to be 525mb, do you think I would be better asking the pro printer to do the upscaling for me?
 
sherbs79 said:
So is there a chance that at 300PPI the picture won't look great??
Click to expand...

If it is 60 inches wide you are after then probably the best PPI will not be 300 due to all the extra pixels you have to make up.

sherbs79 said:
The dimensions before I resize are 5984 x 2738 and after resizing it is 5476 x 2738
Click to expand...

However, I may have got the wrong end of the stick, do you want the image to be 60 inches wide or 60 centimetres wide???

Your pixel sizes in the above quote don't really apply to either but it is close to centimetres, which would look fine and I'd recommend you do the upsizing at home.

Tell me how big you want the picture and I will tell you the pixel dimensions you need it to end up at and how to do it.
 
Craig_85 said:
If it is 60 inches wide you are after then probably the best PPI will not be 300 due to all the extra pixels you have to make up.



However, I may have got the wrong end of the stick, do you want the image to be 60 inches wide or 60 centimetres wide???

Your pixel sizes in the above quote don't really apply to either but it is close to centimetres, which would look fine and I'd recommend you do the upsizing at home.

Tell me how big you want the picture and I will tell you the pixel dimensions you need it to end up at and how to do it.
Click to expand...

They want a 60 inch x 30 inch canvas so I think it might be better to leave the upscaling to the pros?
 
So your original image is 5984 x 2738.

The first element to think about is what size does that relate to at different PPI's (Pixels Per Inch). Here I am taking the image width in pixels to give us the longest dimension of the print.

For example, at a resolution of 300ppi, you divide 5984 by 300 = 19.95".

At an even more fine detailed print of 360ppi the image would shrink, because you have packed those pixels in more densely, 5984 by 360 = 16.62".

At a lower PPI the image enlarges, without creating any more pixels, just because you are spreading them out thinner across the page, for example at 240ppi, 5984 by 240 = 24.93".

As you can see at the recommended 300ppi for fine detail to be visible at close viewing distances your print is about 20" wide, which is one third of the width that you want it to end up to be. Obviously the second thing to think about is how am I going to get my image up to 3 x the width. Is is by allowing the ppi to drop, or by using enlargement software that creates new pixels, or a combination of the two?

Unfortunately if you stick to 300ppi you don't just need 3 x the pixels, because the picture isn't one line going across the page, it is a rectangle. So, the calculation is roughly this, width first, 60(") x 300(ppi) = 18000. Then height, 30 x 300 = 9000. Then to get the total pixels, 18000 x 9000 = 1,620,00,000. Well your original image was only 5984 x 2738 which equals 16,372,224. Therefore the new image is 10 times the size. Meaning for every pixel that exists in your photograph you are adding 9 more that didn't exist.

This is too much for me, I would rather uprez a bit then let the PPI drop.

As @Box Brownie suggests probably time to talk to the printers, or take my advice and do some test prints from a crop of the image.
 
With that level of upscaling I surmise the viewing distance relationship to PPI will be considered. That size of print will best (?) viewed from at least 6 feet away, you might be able to print as low as 150ppi and not 'see' any loss of quality.

Were I you I would be talking to the specialist printer and hopefully they will "know what they are doing......"
 
Yes I think you may be right! I will email them on Monday and hopefully they can advise me on what to do! Thanks for all the help folks, still can't get my head around this so back to the books and YouTube I go!! [emoji85]
 
I look forward to your updating this thread following your discussions with the printer.........and all being well just how good the final print is.

FWIW at 150ppi and the dimensions you mention the upscaling will be approx x2 and that I think I recall reading in the past is not unreasonable when done well.
 
At 6 feet, the eye can't resolve better than 120-50dpi (source). If you take an average of say 90, that'll mean you can print (5984 x 2738 = ) 66" x 30" without mucking about with resizing.

I'd be inclined to get a couple of test prints done at different resolutions (one at native, one upsized to 150dpi and one to 300 if you're going to have people pressing their noses against it to check for quality) to see which looks better if it's financially viable. A reputable printer should be able to do an A4 sized "section" of the print on proper paper which can be used to sample the quality. If you're spending that much on a print - it's best to get it right first time.

Edit to add - Should have read the replies...
Craig_85 said:
do some test prints from a crop of the image.
Click to expand...
This.
 
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Canvas is also more forgiving of lower pixel counts than flat papers. Best bet would be to talk to the printer and see what they recommend you do.
 
The printer will know how to get the best result from his own equipment. Be guided by him.
What he tells you may not apply to another printer who works differently.
 
Thought I would update on this! I spoke to the printer and they asked me to send the file over at 300ppi and they would check that it could be printed at 60" x 30", they then sent me out some proofs of the print on paper and canvas free of charge, proofs looked ok! Picked the canvas up on Tuesday and it looks amazing! Client is very happy and already has it hung in their house!! Good job all round! Thanks again for all the tips and pointers

Scott
 
There you go. All this talk of 300dpi is rubbish so many articles say disregard it and my own experience of it is that it is not relevent.
 
sherbs79 said:
Thought I would update on this! I spoke to the printer and they asked me to send the file over at 300ppi and they would check that it could be printed at 60" x 30", they then sent me out some proofs of the print on paper and canvas free of charge, proofs looked ok! Picked the canvas up on Tuesday and it looks amazing! Client is very happy and already has it hung in their house!! Good job all round! Thanks again for all the tips and pointers

Scott
Click to expand...

shapeshifter said:
There you go. All this talk of 300dpi is rubbish so many articles say disregard it and my own experience of it is that it is not relevent.
Click to expand...

Great looking canvas :)

I can only surmise that the lab upscaled as appropriate.......... and made that nice client acceptable print ~ a good result.
 
shapeshifter said:
There you go. All this talk of 300dpi is rubbish so many articles say disregard it and my own experience of it is that it is not relevent.
Click to expand...
Indeed. The original image was about 6000 pixels across, and the final print is 60 inches across, so that's about 100 pixels per inch. (It doesn't matter whether the image was upscaled before printing; the bottom line is 100 "genuine" pixels per inch.) That's about the practical maximum for printing on canvas, so it should look good.

The 300 ppi "rule" relates only to images which are being inspected closely. That's about the maximum resolution which somebody with 20/20 vision can achieve at minimum focus distance. The bigger the image, the further away you tend to want to view it, and the required resolution drops accordingly. In practice, any sharp image from a modern camera can be printed as big as you like and it will look fine.
 
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For an image to be printed at 60x30in at 300ppi, it should be 18,000x9,000px. Which is a far cry from your original image of 5984x2738px. Upscaling and dropping PPI (pixel per inch) will allow you to print at a bigger size. However, expect image quality to suffer. So think about how much of a decrease in quality will acceptable for you considering viewing distance and all. It's best to ask the print lab. They would probably give you a preview and some recommendations.
 
FWIW I recall a good few years back a discussion with a photographer who was using a 5MP camera and the files were being used for billboard sized prints..................seen from >100 feet away they were deemed to be fine, no idea what the PPI was but possibly under 30??? NB don't bother to calculate as I think he said there was some uprezzing applied ;)
 
KennethLi said:
For an image to be printed at 60x30in at 300ppi, it should be 18,000x9,000px. Which is a far cry from your original image of 5984x2738px. Upscaling and dropping PPI (pixel per inch) will allow you to print at a bigger size. However, expect image quality to suffer. So think about how much of a decrease in quality will acceptable for you considering viewing distance and all. It's best to ask the print lab. They would probably give you a preview and some recommendations.
Click to expand...
The 300 dpi is a myth it counts for zero.
 
shapeshifter said:
The 300 dpi is a myth it counts for zero.
Click to expand...
300 dpi just so happens to be a buzzword in print. As it is what most printers require. However, other print factors such as viewing distance, content of the image, and medium for printing must also be considered. That's why for such large prints, 300 dpi requirement is disregarded; Hence the samples and previews provided.
 
sherbs79 said:
The dimensions before I resize are 5984 x 2738 and after resizing it is 5476 x 2738
Click to expand...
.??

Shouldn't the 'width' remain the same? Surely that's using the maximum amount of your original file
 
sherbs79 said:
The dimensions before I resize are 5984 x 2738 and after resizing it is 5476 x 2738
Click to expand...
Phil V said:
.??

Shouldn't the 'width' remain the same? Surely that's using the maximum amount of your original file
Click to expand...
What he's done is crop to a 2:1 aspect ratio. Before, it was slightly longer / thinner than that (2.186:1); after, it was exactly 2.000:1

At least, I hope that's what he's done. I hope he hasn't stretched the image instead of cropping. But we don't have enough information to be confident of that.
 
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StewartR said:
Not true. The figure of 300 ppi (note: ppi, not dpi) has a solid basis in science which I explained earlier:
Click to expand...

Yes. I have misused "buzzword" and dpi (my mind goes to that term when it comes to print/printers). I meant "common" or "prevalent" as it is what print labs require. I agree with your explanation regarding the application of the 300 ppi "rule". That's why I mentioned that for larger-sized images other factors come into play (such as viewing distance) that allows for decrease in ppi.
 
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