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Author Topic: shrinking files without quality loss  (Read 807 times)

Eric Brody

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shrinking files without quality loss
« on: July 08, 2018, 07:58:20 PM »

I have an incredibly detailed image made with a 42MP camera which I'd like to get printed at Costco. They do 24x36 luster prints on an Epson 78xx for US$10! My Epson 3880 will do only a maximum of 17" wide.

I have their profile, made the image 8 bit, and resolution of 180 but it's still 80MB. How can I bring it down to the 10MB Costco says is their maximum file size?

Any suggestions would be greatly appreciated.

Eric
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Mark D Segal

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Re: shrinking files without quality loss
« Reply #1 on: July 08, 2018, 08:52:39 PM »

You can probably get away with 180 for that print size, but probably not a good idea going lower, even given that the photo will be large enough to be viewed from a bit of a distance. Then there is a question of the colour space you are using. 8-bit/180PPI in ProPhoto, for example, could turn out to look quite disappointing. If you value the detail of that 42 MP camera, it's a shame to lose it because Costco makes cheap prints from degraded files. If you think the print is only worth ten bucks I suppose you could convert it to JPEG and let the conversion algorithm discard data and compress the file till you meet their limit. Depending on the photo perhaps it may not even look too bad, but no guarantees. If you really value the integrity of the original file it would probably make more sense to spend some additional dollars using a proper professional printing service that doesn't impose such limits on file size.
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Mark D Segal (formerly MarkDS)
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Eric Brody

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Re: shrinking files without quality loss
« Reply #2 on: July 08, 2018, 11:26:43 PM »

Thanks for your reply Mark. I have done these Costco prints as tests and as part of working through my temptation/desire to purchase a 24" printer for myself. I use them to try to see how good a "real" print might be. My local emporium charges orders of magnitude more for such a print, and obviously it would be quite a bit better (I'd hope at $126 for a 24x36 image). I know I probably cannot make even a 13x20 on 17x22 Platine for $10. I was just looking for a quick way to make them work for this purpose.
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Mark D Segal

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Re: shrinking files without quality loss
« Reply #3 on: July 09, 2018, 12:00:23 AM »

Given how cheap they are, perhaps just try a few approaches for getting the files down to 10MB, hand them in and see what comes back. Sometimes one can be pleasantly surprised.
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Mark D Segal (formerly MarkDS)
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langier

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Re: shrinking files without quality loss
« Reply #4 on: July 09, 2018, 12:21:01 AM »

With a price of only $10, I'd simply try saving a jpeg of your image at 180 ppi, the proper output file for their paper and as close as I could get it to 10 MB, send the file to them and see what I got. The results may surprise you. Of course, with your particular file, YRMV.
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BobShaw

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Re: shrinking files without quality loss
« Reply #5 on: July 09, 2018, 04:42:17 AM »

If you have a Mac then just open the file with the Preview app and go File / Export and if you pick JPG then you can dial in whatever size you need using the slider.
You can do similar in photoshop.

BTW "Quality" does not (at least in engineering) mean high resolution or better. It means fit for purpose. So an 80MB file is actually less quality than a 10MB file if the requirement is for a 10MB file. A Fiat 500 is higher quality than a Rolls Royce if the requirement is that it fits into a 2m parking spot in Rome. (;-)
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Redcrown

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Re: shrinking files without quality loss
« Reply #6 on: July 09, 2018, 10:47:22 AM »

Double check the file size limit. My Costco has no such 10mb limit. I've uploaded 30mb jpegs with no problem. Takes about 25mb for a 24x36 inch image at 300ppi. I don't see anything on the CostcoPhoto help pages about a file size limit.
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Frans Waterlander

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Re: shrinking files without quality loss
« Reply #7 on: July 15, 2018, 02:00:53 AM »

This is a little late, but Costco has a 50MB limit.
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NAwlins_Contrarian

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Re: shrinking files without quality loss
« Reply #8 on: July 20, 2018, 01:00:10 AM »

I have an incredibly detailed image made with a 42MP camera which I'd like to get printed at Costco. They do 24x36 luster prints on an Epson 78xx for US$10! My Epson 3880 will do only a maximum of 17" wide.

I have their profile, made the image 8 bit, and resolution of 180 but it's still 80MB. How can I bring it down to the 10MB Costco says is their maximum file size?

Any suggestions would be greatly appreciated.

IIRC, with Costco all you can upload is a regular JPEG, although you can convert it to the specific Costco location's specific printer's profile, as downloaded from Dry Creek. Anyway, at 8 bits per channel, the full (uncompressed) size from your 42 MP camera would only be a little under 121 MB, so the JPEG compression would have to be a little over 12:1. I suspect you'd find that even a relatively detailed subject may look quite good from a JPEG with 12:1 compression. Certainly for $10 I recommend you try it and see.

Anyway at 24x36 inches you only have 221 ppi to start with, so going down to 180 ppi only reduces your pixel count by about 34%, so the compression would still be about 8:1--which again I think may very well look fine. And I think that a good 180 ppi would very probably look fine in a print that large. However, I suspect you're likely to get overall better results by sending 221 ppi compressed 12:1 than you are sending 180 ppi compressed 8:1.

Now if in fact the limit is 30 MB or 50 MB instead of 10 MB, then you should be fine regardless. Even 4:1 compression (for 30 MB) in a JPEG will usually be pretty close to visually lossless / indistinguishable.
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