Image resizing
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#1. "RE: Image resizing" | In response to Reply # 0
elec164 Nikonian since 15th Jan 2009Fri 26-Jan-18 04:52 PM | edited Fri 26-Jan-18 04:59 PM by elec164Michael there is substantial information missing to give exact advice.
For example,,, you say you are creating JPEG's from raw files at 300 PPI,,, but don't say which body you are using. You list a D300s as your main body which at 12 MP and 300 PPI would result in an image approximately 9.5" x 14.3".
You say a sample file size is 46" x 73",,, but that doesn't tell us what PPI to decide what MP image we need. But if it's at 300 PPI,,, then you have a long haul to get the D300s 12 MP up-sampled to the size needed. Up-sampling to 150 PPI would be more realistic,,, but we don't know if that will be acceptable to the printer.
So a bit more info is needed.
As to programs,,, years ago there were specialized software that did a substantially better job then say PS. I used Genuine Fractals. It was a PS plug-in that did somewhat better up-sampling then PS did. But today,, I don't know that if a separate program is need in that Adobe has done a substantial improvement to it's re-sampling algorithms.Pete
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#5. "RE: Image resizing" | In response to Reply # 1
MValentine Nikonian since 07th Jun 2002Sat 27-Jan-18 05:34 PMI need to update my equipment listing. These images were shot with a D750 and generally a Tamron 70-200 f2.8Visit my Nikonians gallery
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#10. "RE: Image resizing" | In response to Reply # 1
rbaskin Nikonian since 05th Feb 2007Thu 01-Feb-18 08:24 PMGenuine Fractals became On1's Perfect Resize and does a great job. By coincidence,just yesterday I had a conversation with a printer who regularly does 5 to 6 foot prints for clients and he swears by Perfect Resize. He uses Photoshop for everything EXCEPT resizing.
To be sure, large cling prints will have different reqs than fine art printing, but you still need the right tools to do the best job.
Ralph in CT
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#2. "RE: Image resizing" | In response to Reply # 0
* File size in either pixels or inches. Length and width.
* Print resolution in pixels per inch, do not confuse this metric with dots per inch. PPI represents the density of pixels in the image, DPI is the density of ink dots on the printed page.
* File format - Tiff, Jpeg, PSD. The most universal with the best quality is TIF since it can be saved without compression and is a true image format.
* Color space. Most print bureaus can work in sRGB, but sometimes they prefer the images be converted to their custom ICC print profiles. If you can get access to these you also have the benefit of editing the images with soft proofing to verify the color, tone, and contrast that will be produced in the print.
Ernesto Santos
esartprints.com Ernesto Santos Photography
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#4. "RE: Image resizing" | In response to Reply # 0
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#6. "RE: Image resizing" | In response to Reply # 4
Mithel Registered since 12th Mar 2017Sat 27-Jan-18 06:16 PMEven with my D810 to make a six foot wide print, for an ideal situation (perfect fit to the image frame) the best I'd be able to get would be 100 ppi. Not exactly crisp but perhaps acceptable depending on the location and content of the image.Visit my Nikonians gallery.
#7. "RE: Image resizing" | In response to Reply # 0
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#8. "RE: Image resizing" | In response to Reply # 7
Mithel Registered since 12th Mar 2017Sun 28-Jan-18 08:16 AMAn image that is "low resolution" and looks poor at 12" away may look just great in a window display where people are viewing it from a significant distance.
One trick I've done when upsizing a photo is to use Capture One (or you could use any good software like Affinity Photo) and do some tweaks like applying a gradient to add more detail at the larger size. Think of it this way: if you have one pixel and you upscale it to double the size you have a 2x2 square of identical pixels (unless your software is intelligently upscaling) then apply a gradient to that 2x2 and each pixel becomes slightly different. Voila... "higher resolution".Visit my Nikonians gallery.
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#9. "RE: Image resizing" | In response to Reply # 7
elec164 Nikonian since 15th Jan 2009Sun 28-Jan-18 09:09 AM> I will be speaking directly
>with the firm doing the printing in order to get a better
>understanding of their requirements. I would think that they
>must have dealt with this issue previously.
They probably have. But most people there you would talk to might not know much more than you and will just give you a canned standard answer to your query. And if you press them for specific explanations,, you'll probably get a blank stare with a shoulder shrug.
It would help to know what type of equipment will be used to make the window cling. For example offset commercial printing would require about 1.5 to 2 times the line screen in image resolution. Typical line screens are 85 LPI for newsprint, 100 to 150 LPI for typical magazine and 150 to 200 LPI for fine art magazines. using the typical magazine with LPI of 100 would require an image resolution between 150 and 200 PPI. Dye-sub and silver halide prints would max out at around 300 to 400 PPI. Ink jets get more complicated due to the Stochastic Dither that's used,,, but generally the lowest PPI for them would be 150-180 PPI for acceptable prints.
As to resolution,,, there are two aspects. One is having sufficient resolution to avoid pixelation. The other is spatial resolution. You can up-sample an image to avoid pixelation,,, but that up-sampling won't add any spatial resolution.
Hopefully when you talk to them,,, you get someone knowledgable.Pete
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#11. "RE: Image resizing" | In response to Reply # 0
One thing that I have found in my tinkering in Lightroom is that it will allow you to define at export the size in inches along with the other perimeters. The file size increases accordingly. What is taking place here and how does it reflect on printing, I am sure their must be limitations. Again this issue is all new to me so I have no knowledge in the area of BIG enlargements.
Thanks for your responses.
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#12. "RE: Image resizing" | In response to Reply # 11
Mithel Registered since 12th Mar 2017Fri 02-Feb-18 02:23 PMCapture One also allows you to specify dimensions for the output and will automatically resize your image for you. (that doesn't guarantee the results will be acceptable)Visit my Nikonians gallery.
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#13. "RE: Image resizing" | In response to Reply # 12
MValentine Nikonian since 07th Jun 2002Fri 02-Feb-18 03:06 PMThank you. I also see that On1 Photo RAW 2018 has a Re-Size feature. I am just trying to get a better understanding as to how these should be used and how they differ. how does one compare to the other and to Lightrooms export sizing. I see that many of the pro printing services do very large image printing which to me would suggest that they are using a software application which runs against the submitted image file. For those that do printing and offer sport options they offer Wall Clings which go life size up to 72". I realize that their are limitations but I doubt theses are originating from medium format high megapixal cameras.Visit my Nikonians gallery
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#14. "RE: Image resizing" | In response to Reply # 13
Mithel Registered since 12th Mar 2017Fri 02-Feb-18 03:39 PMI agree, it's a great question. It would be very nice to know how the various programs compare in their ability to "upscale" and produce desirable quality.
Did you ever contact the printing company you are working with? Do they perhaps use some software themselves?
Obviously it would be best to upscale before any information is lost (i.e. as close to the original RAW file as possible)Visit my Nikonians gallery.
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#15. "RE: Image resizing" | In response to Reply # 14
MValentine Nikonian since 07th Jun 2002Fri 02-Feb-18 03:50 PMI have been emailing back and forth with the individual who is handling the designing and printing, I believe. We are having some polite disagreement on print size capabilities. This is not a print service such as MPIX, Millers, MyPhotoPipe etc. I must be careful as to what and how much I say to them as I am just trying to assist a local agency with this project by providing my photographic services.Visit my Nikonians gallery
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#16. "RE: Image resizing" | In response to Reply # 15
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#17. "RE: Image resizing" | In response to Reply # 15
rbaskin Nikonian since 05th Feb 2007Sat 03-Feb-18 08:15 AMI went to the web site of the printer I had the conversations with Beacon Fine Art Printing and here is his comment on scaling from his 'preparing files for printing' section of his blog:
SCALING: In all cases, scaling an image whether going larger or smaller will always affect the pixels in the image. Making an image smaller is less problematic than making it larger. That said, it is often unavoidable but when doing so understand that when scaling an image more than 50% larger than its original image size the results may be undesirable. You may see artifacts, pixilation and blurring (softness) in the image. There are a few tricks that we professionals use to optimize the process so I would strongly suggest that if you need an image larger than it's native size, leave it to me to handle that. I will tell you the best size for the enlargement and ensure the best quality.
So to me, the big question for the printer is: "Will you do the scaling from a high resolution file?"
Ralph in CT-
#18. "RE: Image resizing" | In response to Reply # 17
MValentine Nikonian since 07th Jun 2002Sat 03-Feb-18 08:21 AMThank you for sharing. This is what I am concluding, the high quality printers have the knowledge and tools for enlarging and know when to say enough is enoughVisit my Nikonians gallery
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#20. "RE: Image resizing" | In response to Reply # 18
elec164 Nikonian since 15th Jan 2009Sun 04-Feb-18 04:04 PM>quality printers have the knowledge and tools for enlarging
>and know when to say enough is enough
One would hope so!
I went to the linked Beacon Fine Art Printing guide and after reading the 'Resolution' section was less then impressed. First,,, he use DPI where he should be using PPI for clarity (but then many do that). He also sustains the myth that 72 DPI is for web which is based upon the misbelief that monitors display at 72 PPI.
He also seems to rely on the often stated 300 PPI which is often suggested as the limits of human visual acuity. He’s using Canon Pro Inkjets which are capable of printing higher resolutions then 300.
I also have issue with “most digital cameras will produce images at 72 DPI”. Yes some cameras may put a tag in the EXIF info as to PPI,,, but that is meaningless and has nothing to do with the native resolution of the camera.
As to the Scaling section,,, I think it’s important to point out there is a difference between scaling/resizing and resampling/interpolating. The former stretches or shrinks the pixels to fit the desired output dimensions whereas the latter adds or subtracts pixels.
I also may have issue with the “In all cases, scaling an image whether going larger or smaller will always affect the pixels..”. It depends on what he means here. Scaling doesn’t change the information in the file. And a pixel as a data point has no physical dimensions. It’s only when rasterized to an output device that it takes on physical dimensions. So if by "affecting" he means resizing,,, then I can go along with that.
Going back to the resolution statement about cameras and 72 PPi. As an example,,, your D750 native PPI resolution is about 4256. But remember the sensor is only about .94”x1.4”. Scale that to 8”x12” and it’s about 501 PPI. If you scale it to the 300 PPI tag that Nikon puts into the EXIF it would result in a print 13"x20". Scale it to 46"x73" and that’s about 82 PPI. Now that 82 PPI might be fine if the window cling is being used on a second or third story window which would prohibit close up viewing. But a street level storefront window,,, it would be woefully inadequate. With a Canon Inkjet,,, I would not go below 150 to 180 PPI ( I haven’t tested the Canon yet,,, but with my HP I would say 150 and the Epson R3000 180). So no doubt one of the tricks he refers to might be upsampling the 82 PPI so that it’s at least 180 PPI then resharpen. It would be better to upsamlpe it further,,, but then you could run into other issues depending on the program used. While upsampling cannot add fine detail that isn’t there to begin with,,, it can help with the jaggies or stair stepped appearance of diagonal lines. It's a bit dated,,, but I found this comparison between different programs.
Another potential troubling point is with what’s captured. For instance,,, if the scene contains depth and you used the standard DOF table or calculator,,, that will be a problem in how they might be evaluating the enlargement and determining it unsuitable. For example if you shot the scene using a standard calculator for an 85mm lens focused at 30’ and f/5.6,,, it would predict a DOF of about 11’. But that’s for an 8”x12” enlargement viewed at about 10”. Now make a 46”x73” enlargement viewed at the same 10” you’d only have a DOF of just under 2’. To get the same DOF at the 10” viewing distance for the 46”x73” enlargement you would have to shot it at f/32 instead of f/5.6.
So as you can see,,,, there are a lot of variable factors missing in the OP. And without knowing the settings for the image being used nor the equipment and requirement of the printing service,,, there’s just to many variables to make an exact determination.Pete
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#21. "RE: Image resizing" | In response to Reply # 20
Mithel Registered since 12th Mar 2017Sun 04-Feb-18 04:22 PMVery nice discussion Pete.Visit my Nikonians gallery.
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#22. "RE: Image resizing" | In response to Reply # 20
rbaskin Nikonian since 05th Feb 2007Sun 04-Feb-18 04:30 PMI understand your points.
I've seen his work and have talked to people he's worked with. His philosophy is to work one-on-one with a client to set the expectations and desires, working with proofs to ensure good outcomes.
re: 300 vs. 150 vs. 360 vs. ???. In a workshop with Vincent Versace, he strongly advises an even divisor of the physical printer's max. For Canon that means 150 or 300, for his preferred Epson, it's 180 or 360.
I'm of the view that the printer knows his/her equipment, mediums and outcomes best and should provide guidance that provides the optimum file for their work together. A large art print would have significantly different requirements than window cling.
The theory and math are important, but knowing the resulting impacts is the key IMHO.
Ralph in CT-
#23. "RE: Image resizing" | In response to Reply # 22
elec164 Nikonian since 15th Jan 2009Sun 04-Feb-18 07:12 PM>I've seen his work and have talked to people he's worked with.
Please forgive me if I gave the impression that he's work might be substandard. I'm sure he puts out quality work!!
My comments where about his prep page only. And truth is at one time I once believed in much of what he said,,, that is until I started researching and experimenting.
>re: 300 vs. 150 vs. 360 vs. ???. In a workshop with Vincent
>Versace, he strongly advises an even divisor of the physical
>printer's max. For Canon that means 150 or 300, for his
>preferred Epson, it's 180 or 360.
That suggestion has been around for some time and I believe the thought behind it is that printers can only print a dot or not print a dot. It can't print half dots. But there's one thing about that,,, inkjets use many dots to makeup one pixel. And pixels are square not round. In my experimentation it doesn't seem to make much difference. If you follow that thought line and feel it provides better results,,, by all means keep doing it. Doing the evenly divisible doesn't hurt,,, but you should always go up not down. I believe it was in one of Schewe's books or musings where if I recall correct says something to the effect that "one is always better of with the original resolution unless other mitigating circumstances suggest otherwise". But then he contradicts that elsewhere where he suggest upsampling to the inkjets native PPI resolution,,, for which I have determined that there isn't one. But his recommendation for Canon would be that if the native PPI of the file is below 300,, interpolate up to 300. But if it's above 300,,, then you may want to interpolate up to 600.
>I'm of the view that the printer knows his/her equipment,
>mediums and outcomes best and should provide guidance that
>provides the optimum file for their work together. A large
>art print would have significantly different requirements than
>window cling.
Without question I whole hardily agree here. And I agree with his suggestion on his prep page that if you are not knowledgable or experienced with resampling for a given output,,, it's best you leave it up to him. One thing that might change things a bit is if he had a custom RIP built instead of using the standard one in Canon's drivers. I didn't see any mention of that in his site.
Bottom line is these companies reputations are at stake here. If you give them a file and they don't feel it would result in an image of acceptable quality by their standards,, then they will not print it no matter how much you protest. And I don't blame them for that,,, after all it's their reputation on the line.Pete
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#24. "RE: Image resizing" | In response to Reply # 0
The ultimate output and use make a big difference in what is acceptable. For example, the Media Tent at the PGA Tour Championship had a huge photo as a backdrop on one wall. It must have been 30 feet long. From a distance of 10 feet - a typical viewing distance - it looked great and had wonderful detail. When you moved up close it was highly pixelated - almost like a newspaper photo. But the image was perfect for the intended use - a wall in a very large area. My take is the image was a good DSLR photo with normal upsizing.
You want to resample instead of just resizing your image. This is a small distinction because it means that algorithms to change size and sharpen the image with minimal noise are being used. Which algorithm depends on the image and whether you are moving to a larger or smaller size.
If the vendor is unfamiliar with upsizing and size requirements, they probably will need to make a test print of equivalent resolution. So I'd plan to provide a test file of an important detail using the same resolution as the final print. So if you are making a 73" wide final print, make a test file 18" wide with one quarter width of the original image. For a D750 image, that's a crop that is 1500 x 1000 pixels to produce an 18 x 12 print.
I suspect that upsizing using your normal software will be fine. Adobe has several algorithms for resizing. Lightroom would typically use Bicubic Smoother for upsizing an image. Just export the file to the desired output size and the resulting file should be fine.
If you are using Photoshop, you'll need to manage the process a bit more. You are resizing rather than exporting, and you need to resample as part of that process. Your default preferences may specify a resampling algorithm that is not appropriate, so be sure to change your settings to Bicubic Smoother for enlargement. You should use Preserve Detail if that option is available.
If you are asked for resolution of your output file, you probably want to specify at least 180 ppi or higher. The optimal resolution will depend on the printer, the output media, etc.
There are several upsizing programs you can use if you are not satisfied with output. The most popular are Alien Skin Blow Up, Perfect Resize, PhotoZoom Pro, and Qimage Ultimate. But Lightroom or Photoshop should be fine for this kind of situation.
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