So I've got 6x9 negs that were scanned with an imacon at 3200, some of the images were cropped into a little bit. Basically a gallery wants to sell larger prints at 39x26 and the images don't have the resolution to print at 300dpi, because the print will be so large I know the viewing distance changes. What are your thoughts on the difference between 300 and 240 and should I interpolate up or print at 240dpi
The images are long exposure taken at night so the clarity is already a little skewed but any suggestions would be appreciated. Thanks
You will not see any difference between 300 and 240. You can even go down to 180 and you will probably still see nothing. Have a test print made and see for yourself. Very nice work btw.
Thanks Peter, that is just the sort of response I was hoping for. Now for the nitty gritty, because of cropping each image slightly differently they all have their own special resolution. At 39x26 they vary from 243.654 to 255.052 I'm making these numbers up but what I would like to know is this
1- I like the idea of printing at the size desired and allowing each one to print at whatever res they are at that size. Changing the res to 240 just because it's a nice round number is actually still going to do algorithmic resampling and mess with my native scan no?
2- Is it possible to print with a dpi that has three decimal places in it?
I know this sounds a bit neurotic but I would gladly avoid resampling if not needed.
Also, I'm sure this has been beaten to death, do the epson printers actually print more than 240? I was told just now by my printer it doesn't matter above 240 and that if you give them a print at 300 they'll print at 240 anyways
mollusk222 wrote:
Also, I'm sure this has been beaten to death, do the epson printers actually print more than 240? I was told just now by my printer it doesn't matter above 240 and that if you give them a print at 300 they'll print at 240 anyways
The optimal input resolutions for Epson printers are 360 and 720 ppi for printing at 1440 dpi or higher. If your app queries the printer driver, that is what it will request. HP and Canon printers work at 300 and 600 ppi input.
The input ppi and output dpi are related, but separate issues.
Printing apps like Qimage (Windows only) will automatically uprez the image to the printer's requested resolution. In apps like Lightroom, you can set the input resolution value, and it will then automatically uprez on output to the printer.
And even though the Lightroom and Qimage algorithms are much better than the OS/driver ones, you would have great difficulty seeing the difference of 300 vs 360 without a loupe.
And it has been beaten to death for at least 12 years, and still some remain unconvinced.
I have an Epson 9900 and while the native resolution is 360 (and 720 for one specific setting) the reality is that you'd be really hard pressed to see any difference above 180. The scans can and will make a difference - the difference between okay scans and great scans but the difference between 240 and 360 probably won't make much difference. There are some who advocate uprezzing everything to 360 in Ps for that print, but I've never seen an actual difference. Again, make a couple of test prints and you'll soon see for yourself.
It's important to know what the optimum type of file to send to your printer is, which for the Epson's is typically 360, but to also know that you can get away with less when needed.
I did resolution tests with a target that measured lp/mm on the 9900 with glossy transmissive media and was able to see about 9-10 lp/mm on the printed piece. Was also able to see gradually increasing resolution all the way up to 1440 dpi, but that was with a synthetic target and a real world image would no doubt yield considerably less.
Peter, I have a local printer who has made her 9900 available to me. Do I need to resize my files to Epson's native 360 PPI or will the printer simply accept my 240 or 300 PPI file and NOT uprez using its own software? I have not been able to get a conclusive answer and have read that if uprez occurs that it is better to treat the file using Ps or Perfect Resize. Thanks for your response.
mirabalj wrote:
Peter, I have a local printer who has made her 9900 available to me. Do I need to resize my files to Epson's native 360 PPI or will the printer simply accept my 240 or 300 PPI file and NOT uprez using its own software? I have not been able to get a conclusive answer and have read that if uprez occurs that it is better to treat the file using Ps or Perfect Resize. Thanks for your response.
Not Peter, but here’s my two cents worth.
The printer will accept almost resolution you send to it. Since it screens and dithers from its native resolution, somewhere in the print pipeline that has to be done. It would appear that this is done by the OS and very probably using a very basic interpolation algorithm such as nearest neighbor.
If the interpolation rate is high, say going from 120 ppi to 360 ppi, then you will be able to see a qualitative difference between letting the ‘pipeline’/driver/printer handle everything compared to interpolating and applying output sharpening using better algorithms from Lightroom, Qimage, or even Photoshop.
Even comparing side by side prints, I doubt you would be able to see any difference throwing 300 ppi to the printer and upping and sharpening yourself. And probably (depending on the image), you would see little or no difference between 240 ppi and 360 ppi.
On the other hand, if all you have to do is check a box in Lightroom and set a field to 360 ppi before you press the print button, why wouldn’t you do that? At worst you see no difference, at best you do.
If you are not printing from an app that can automatically interpolate and sharpen for print, and you want to be sure that your print will look good, then do hard proofs of 100% crops on 8.5” x 11” sheets. The 9900 will take letter sized sheets with no problem, although it does have a tendency to skew them at times.
As Brian says and I have said previously, it really won't make any difference. If you want to be safe, and you seem overly cautious, make copies of all your print files and rez them to 360 dpi at the final print size. Because your friend has made the printer available to you, just make a full size test print on a 44 inch roll. A print that size will probably run you seven or eight dollars, maybe ten at the most. You'll see everything in context and you'll have all your answers. I've made thousands of prints on that printer over the last six years and have never - even looking closely at the print with reading glasses - seen any degradation in image quality printing at any dpi as long as it's above 180. I've often made large prints at 150 dpi and they look fine too. Below that you do start to see pixelation in diagonals. 180 is the accepted "safe" resolution because it's exactly one half the number of nozzle per inch in the print head. A good rule to follow. Go print and enjoy your new prints.
Brian and Peter, thank you both for your responses. I am just now learning about the printing process and the workflow involved. From your responses it appears then that regardless of the file's ultimate resolution, the printer will interpolate at print time if it does not receive the file in its native (360ppi) resolution. And because Peter indicates there is no appreciable reduction in quality at any resolution > 180 ppi, then it really does not make a difference whether I interpolate at export or if I just let the printer take the file at its given resolution and let it interpolate to the required resolution. If I have it wrong please let me know at your convenience.
That's basically it. There might be certain images, when looked at through a loupe where you might see a very slight difference, but for most people and the naked eye, it just won't matter enough to mention. But again, go make yourself a couple of test prints and see for yourself.
Hey, waitasec....a very common mistake is being made in this entire discussion...
PIXELS-per-inch is NOT THE SAME as DOTS-per-inch!
Pixels per inch is the reference to the density of detail due to the digital sensor matrix or digital scanner matrix.
DOTS per inch is the reference of the density of inkdots that a printer uses to make a single pixel!!!
The Epson 9900 software may have a 'native resolution' of 360 dpi, but it can output its ink at differing densities (resolutions):
2880 x 1440 dpi;
1440 x 1440 dpi;
1440 x 720 dpi;
720 x 720 dpi;
720 x 360 dpi;
360 x 360 dpi
...and it does so in spite of the Pixel count in the file and the final print size. A 3000 pixel wide image could be 10" (300 ppi) or 40" (75 ppi); A 6000 pixel wide image could be 10" (600 ppi) or 40" (150 ppi)
mollusk222 wrote:
So I've got 6x9 negs that were scanned with an imacon at 3200, some of the images were cropped into a little bit. Basically a gallery wants to sell larger prints at 39x26 and the images don't have the resolution to print at 300dpi, because the print will be so large I know the viewing distance changes. What are your thoughts on the difference between 300 and 240 and should I interpolate up or print at 240dpi
The images are long exposure taken at night so the clarity is already a little skewed but any suggestions would be appreciated. Thanks
In large inkjet prints, 240 is quite sufficient — you will not likely see any difference at all. Some feel that the lower limit for usable resolution might be as low as 180.
You can, of course, up-res the files to 300 ppi for printing if you wish. (ppi refers to the resolution of the image file that you'll send to the print. dpi refers to the number of dots per inch that the printer creates with the print nozzles, and is likely to be something like 1440. Yes, you print a 300 ppi file using 1440 dpi printer resolution.)
Peter Figen wrote:
.... I've made thousands of prints on that printer over the last six years and have never - even looking closely at the print with reading glasses - seen any degradation in image quality printing at any dpi as long as it's above 180. I've often made large prints at 150 dpi and they look fine too ...
I can say the same as Peter. In fact, I routinely print at 180 in order to increase the final output size of an image that's already been processed at 300dpi for commercial printing. With Sigma/Foveon images ... and using Sigma's processing software ... the default setting for their "double size" image conversions is 180dpi.
1- I like the idea of printing at the size desired and allowing each one to print at whatever res they are at that size. Changing the res to 240 just because it's a nice round number is actually still going to do algorithmic resampling and mess with my native scan no?
Yes, adjusting image size will require some math. Photoshop has a few to choose from optimized for the content of your image (bicubic sharper, bicubic smoother, nearest neighbor, bilinear, auto...). In my line of work I'm usually using bicubic sharper as I handle magazine content that has to be reduced from FX and medium format cameras down to 10x12" at 350dpi (175lpi). Would any reader notice that I skipped the step of image size reduction in PS and simply place the image in InDesign and allow InDesign to do the math? Absolutely not, but a fancy #2 substrate costs a premium and can hold 175 line screen, you bet I'm going to push out the best I can. Epson software is doing who knows what to convert a file to 240dpi, 360dpi, or 720dpi, so it's best to output your file spec'd exactly to final print output.
Standing back you shouldn't see the difference between 360dpi, 350dpi, 300, 240... You'd need to be 8" away with young healthy eyes and a second print to compare the differences.
So on to paper. Find out what your substrate can actually handle. The offset print vendors I've worked with use plates capable of 200lpi or 400dpi. But only the most expensive of #1 stock can actually hold that resolution. There's an arbitrary scale of paper stock from #1-5, 1 being the best, 5 not so good. If you'll be on Epson paper, find out which one it is as some have a lower resolution and ink limit.
It is always interesting how confused photographers get with this dpi thing. I guess it can be confusing... but it is really simple. Epson printers print at 360 dpi..... you can feed it any dpi you want, but the software in the printer is going to interpolate it up to 360 dpi. Many people feel it is better to use other software to interpolate your file to 360 dpi then to let the printer do it. As others here have said most times you can't tell the difference if you send it 240 and some low detail images 180. Epson reps tell me you should at least send the printer derivatives of 360 for the best interpolation. I personally like to interpolate the image to 360 myself because looking at the image at this size tells me how well it is going to print..... but this is a personal preference.
Canon is the same deal but the native dpi is 300.... but otherwise the same idea. Hope this helps to make it a little less confusing.
Peter Le wrote:
It is always interesting how confused photographers get with this dpi thing. I guess it can be confusing... but it is really simple. Epson printers print at 360 dpi.....
No, they print at 720, 1440, 2880, or 5760 dpi. They accept input at 360 or 720 ppi (pixels per inch).
