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09/06/2005 11:41:27 PM · #1 |
I'm trying to create files for large prints. I'm enlarging the files using the re-sampling method described in the tutorial on this site (ie using bicubic re-sampling and increasing size in 10% sequential steps). To get to the final file, I'd like to decrease the pixels per inch from 300 to 180. When do I do this to preserve best quality? At the start of the process, at the end, somewhere in the middle? I'm assuming that all one needs to do is change the resolution in the dialog box.
Thanks
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09/06/2005 11:44:16 PM · #2 |
Originally posted by joezl:
I'm trying to create files for large prints. I'm enlarging the files using the re-sampling method described in the tutorial on this site (ie using bicubic re-sampling and increasing size in 10% sequential steps). To get to the final file, I'd like to decrease the pixels per inch from 300 to 180. When do I do this to preserve best quality? At the start of the process, at the end, somewhere in the middle? I'm assuming that all one needs to do is change the resolution in the dialog box.
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Why would you want to change the ppi from 300 to 180?
Message edited by author 2005-09-06 23:44:40.
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09/07/2005 04:06:01 PM · #3 |
Originally posted by nsbca7:
Why would you want to change the ppi from 300 to 180? |
Many printing organisations suggest using 150 for large prints (including DPC). Presumably this is to avoid having huge file sizes when printing very large prints as this can cause memory problems during the printing process.
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09/07/2005 04:10:12 PM · #4 |
| Are you trying to print to your own printer or using a print service? |
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09/07/2005 04:12:03 PM · #5 |
ppi rate doesn't change the actual pixels, it only gives instructions to the printer and/or display driver about your desired pixel density. It shouldn't matter at all, when you change the ppi, so long as you can figure out for yourself when you have enough pixels to suit your needs.
Message edited by author 2005-09-07 16:13:56. |
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09/07/2005 04:15:15 PM · #6 |
Usually, you would want to take down photo quality after doing all of your editing, i.e. at the end of the process. But, your process may be a little different since your editing already involves taking the quality down slightly (by enlarging).
It would make sense that during the enlargement process, you'd want to leave as many pixels as possible for the computer to work with. So,
I'd say at the end of your process.
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09/07/2005 04:22:49 PM · #7 |
If you know that you Will be using 180 ppi, I would change it before resizing. But make sure that "Resample Image" is unchecked - that way the pixel count isn't changed, but the print dimensions are effectively increased. If you get it to the final dimesions at 300 ppi and then resize to 180 you are doing more processing than you need to, and you'll lose quality.
Message edited by author 2005-09-07 16:26:27. |
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09/08/2005 10:30:21 AM · #8 |
Originally posted by joezl:
Originally posted by nsbca7:
Why would you want to change the ppi from 300 to 180? |
Many printing organisations suggest using 150 for large prints (including DPC). Presumably this is to avoid having huge file sizes when printing very large prints as this can cause memory problems during the printing process. |
DPC suggests at least 150. My files are between 280 and 300 for the largest print size and are accepted by the system. |
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09/08/2005 11:50:52 AM · #9 |
More ppi equals better quality for a given print size.
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09/08/2005 12:38:04 PM · #10 |
Originally posted by coolhar:
More ppi equals better quality for a given print size. |
... though there is a limit where the quality actually falls off when increasing the ppi. This usually happens when you exceed the max ppi of the printer being used. Things start to look a little muddy at this point.
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09/08/2005 01:04:37 PM · #11 |
Good information of preparing print files for output to Fuji or Noritsu printers available at Dry Creek Photo. Their page on Using Printer Profiles has, at the end, a table of "actual" native pixel dimensions for various printers.
Usually, your best results will come if you use the exact number of pixels, or else an even multiple (or fraction, like either 1/2 or twice) of the native resolution. |
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09/08/2005 01:20:04 PM · #12 |
Originally posted by cpanaioti:
Originally posted by coolhar:
More ppi equals better quality for a given print size. |
... though there is a limit where the quality actually falls off when increasing the ppi. This usually happens when you exceed the max ppi of the printer being used. Things start to look a little muddy at this point. |
I'm afraid that the printer just prints at its own max dpi and increasing the file ppi can do nothing on its own to muddy a print.
edit: if that's what you meant.
Message edited by author 2005-09-08 13:20:37.
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09/08/2005 01:29:43 PM · #13 |
Originally posted by nsbca7:
I'm afraid that the printer just prints at its own max dpi and increasing the file ppi can do nothing on its own to muddy a print. |
If a printer is at 300 dpi, and the file is at 305 dpi, those pixels have to -- at some point -- be interpolated/downsampled, and in this case, those fractional pixels can (not necessarily will) lead to a loss of detail.
Simple math suggests that even multiplications/divisions will result in a more accurate result and greatest retention of detail. Setting the resolution in editing software -- rather than letting the printer do it -- will let you (to some extent) control and compensate for any errors introduced. |
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09/08/2005 01:29:47 PM · #14 |
Originally posted by nsbca7:
Originally posted by cpanaioti:
Originally posted by coolhar:
More ppi equals better quality for a given print size. |
... though there is a limit where the quality actually falls off when increasing the ppi. This usually happens when you exceed the max ppi of the printer being used. Things start to look a little muddy at this point. |
I'm afraid that the printer just prints at its own max dpi and increasing the file ppi can do nothing on its own to muddy a print.
edit: if that's what you meant. |
I didn't mean the printer was doing anything special just that the extra ppi won't be used by the printer and the image could look a little muddy.
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09/08/2005 01:53:05 PM · #15 |
Originally posted by cpanaioti:
Originally posted by nsbca7:
Originally posted by cpanaioti:
Originally posted by coolhar:
More ppi equals better quality for a given print size. |
... though there is a limit where the quality actually falls off when increasing the ppi. This usually happens when you exceed the max ppi of the printer being used. Things start to look a little muddy at this point. |
I'm afraid that the printer just prints at its own max dpi and increasing the file ppi can do nothing on its own to muddy a print.
edit: if that's what you meant. |
I didn't mean the printer was doing anything special just that the extra ppi won't be used by the printer and the image could look a little muddy. |
That's what I thought you meant. That won't happen. There are no extra pixels or dots at the printer end. The printer prints to the resolution it is set at. If the image is only 20ppi the image will look the same if it is printed at 180dpi or 300dpi. Similarly an image saved at 500ppi and 300ppi will come out looking the same if printed at 300dpi.
The dpi, dots per inch, is the rate at which the nozzle of the printer lays down fine dots on the paper or printable media. These do not always necessarily reflect one to one pixel from the file to dot on the page.
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09/09/2005 06:52:30 PM · #16 |
Thanks all. That's very helpful. I think I now have a plan.
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09/09/2005 07:14:50 PM · #17 |
Work up the image in the original size and let the RIP of the printer upsize it for you. It will look much better. That is, if your taking it to a pro lab.
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09/09/2005 07:15:05 PM · #18 |
Originally posted by nsbca7:
That's what I thought you meant. That won't happen. There are no extra pixels or dots at the printer end. The printer prints to the resolution it is set at. If the image is only 20ppi the image will look the same if it is printed at 180dpi or 300dpi. Similarly an image saved at 500ppi and 300ppi will come out looking the same if printed at 300dpi. |
They won't look the same at the same print size. |
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09/09/2005 07:32:36 PM · #19 |
I thinkhe's referrring to the actual print quality, not the resolution of the printed image.
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09/09/2005 07:43:36 PM · #20 |
Originally posted by MeThoS:
I thinkhe's referrring to the actual print quality, not the resolution of the printed image. |
But a 20 ppi image printed at 300 dpi will either be 1/15 the original dimensions (at original quality) or horribly "pixelated" if printed at the specified physical dimensions. |
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09/09/2005 08:01:59 PM · #21 |
I was taking a stab at what me might of meant. I know exactly what your talking about and you are correct. I was giving him the benefit of doubt since I know he knows this as well.
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