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RetouchPRO LIVE "Resolution" with Andrew Rodney

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  #11  
Old 07-03-2011, 02:50 PM
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Doug Nelson Doug Nelson is offline
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

"Resolution" is up on the international rentals page now.
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Old 07-12-2011, 09:32 AM
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

I enjoyed the presentation and learned a lot from it, but on reviewing the handouts, I came across a confusing graphic that does not make sense to me. I am talking about page six of the handout (4th page of "Resolution Basics"). I do not understand how dividing the pixels by the output resolution ("DPI" as labeled in the graphic) translates into document size. If the graphic used the designation "ppi" in place of "dpi" it would make sense to me. My understanding of "dpi" is that this term applies only to the number of dots a printer places on the paper in an inch, thus my Epson printer is theoretically capable of printing 2880 dots per inch, having nothing to do with size. Am I missing something here?

Cliff
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Old 07-12-2011, 10:07 AM
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

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I do not understand how dividing the pixels by the output resolution ("DPI" as labeled in the graphic) translates into document size.
There is a fixed number of pixels you divide into a unit for the print. In the slide, the unit of size is inches (could be mm, cm, etc). On the long axis, there are 3000 total pixels of this image. We decide we will divvy up 300 of our pixels into each inch of output. The output device is 300DPI. The result is a 10 inch print (divide 3000/300 you get 10). If instead we decide we want the output resolution to be 200DPI (use 200 pixels of our data per inch), its now 15 inches in size. If we were sending this to a film recorder who’s output resolution was 1000DPI, out output would be 1 inch in size.

In all examples here, we had 3000 total pixels. But how we divide them up to produce dots from our output device dictates the size. The dot on the film recorder (1/1000 of an inch) is far smaller than the other output device (1/200th of an inch).

In this case, there is a 1 to 1 relationship between a pixel becoming a dot on an output device.
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Old 07-12-2011, 11:41 AM
cliffculp cliffculp is offline
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

OK, I was not thinking in terms of a 1 to 1 relationship since I am accustomed to output devices taking more than a single dot to represent a pixel such as a 300 ppi image printed on a printer with 2880x1440 dpi. Thanks.

Cliff
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Old 07-12-2011, 12:03 PM
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

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OK, I was not thinking in terms of a 1 to 1 relationship since I am accustomed to output devices taking more than a single dot to represent a pixel such as a 300 ppi image printed on a printer with 2880x1440 dpi. Thanks.
That’s sometimes the case, sometimes not. But in the case of an Epson printer as an example (2880x1440), its going to use the size Photoshop currently uses for that print despite the non 1:1 relationship in how it ultimately prints. IOW, Photoshop ‘thinks’ the size is 10 inches because in the Image Size dialog (and PS Print dialog), it sees you are assigning 300 pixels per inch and thus, with 3000 pixels, its considering this to be 10 inches. That gets passed to the Epson driver. The driver says “this is a 10 inch print” and then does its thing to produce a print that size, using 300ppi to produce 2880x1440 dither to make a 10 inch print.
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Old 07-13-2011, 05:45 AM
cliffculp cliffculp is offline
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

Thanks for the further clarification. Communication between Photoshop and the Epson driver are obviously more complicated than the usual explanations suggest. If I still have your attention, I believe that you stated that Epson printers max out at 720 dpi. How does that translate into image ppi? Does this mean that sending a document to the printer driver with a ppi greater than 720 will have no more benefit than one sent at 720 ppi?

Cliff
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Old 07-13-2011, 07:16 AM
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

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Originally Posted by cliffculp View Post
I believe that you stated that Epson printers max out at 720 dpi. How does that translate into image ppi? Does this mean that sending a document to the printer driver with a ppi greater than 720 will have no more benefit than one sent at 720 ppi?
In Lightroom, the max output setting in the Print module is 720. The slides towards the end suggest that if you have a document who’s native resolution is above 360ppi at the size shown for the print template, you’ll get superior output if you set this field for 720 (and set the driver for finest detail). Below 360ppi native, set the field for 360. This is a Lightroom option only!
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Old 07-13-2011, 12:30 PM
cliffculp cliffculp is offline
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Re: RetouchPRO LIVE "Resolution" with Andrew Rodne

Thanks again for your response. I missed the part that linked the 720 ppi max idea to Lightroom. I really appreciate your clarifying the advantages of printing from LR as I frequently switch to PS to print. I now have reason to print from LR with its greater versatility.

Cliff
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