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Old Dec 28, 2002, 7:48 PM   #1
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Default Control print resolution or resample

In general, when using an image editing program for printing (PSP7), is it preferable to set the printer resolution fixed at, say 300 pix per inch and then resize (resample) the input image to fit the desired output size -or- adjust the resolution (within limits--200 to 360 pix per in.) to fit the output image size?

Example:
Given a 3 MP input image (Oly 3020 => 2048 x 1536) and a desired output image of 8" x 10" (on a Canon S900), it seems that no matter what, some loss of image information (quality) will occur either through cropping or through interpolation artifacts (unless 2x or 4x is chosen). So, assuming that some loss due to cropping is acceptable, will the viewed image quality by better by using lower print resolution (200 pix/inch in this example) or by forcing 300 pix/in and resizing and cropping to the 8" x 10" output size.

...and I am aware that Qimage can make these sort of decisions for me, but I really would like to understand the basics before turning my decisions over to software.


TIA
jeff
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Old Dec 28, 2002, 9:20 PM   #2
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Yes and No.....??? Now are you confused. Using PS you have to manipulate the the interpolation of the image. (Size ver: Print)... (PPI verPI?)....

One printing program out there that is much easier than PS7 (I have 6) to use as a printing program, and not designed to replace photoshop is a cheep neet one. Qimage http://www.ddisoftware.com/qimage/ has free down load trial version and it will tell you the print resolution but of course it's up to your printer software to decide what the end resolutions is.
No, I'm not related to Mike or the product, just use it all the time!
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Old Dec 29, 2002, 10:19 AM   #3
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M. Haner-

Perhaps I didn't make the essence of my question clear, so let me try to rephrase it.

When you start out with a fixed number of image picture elements you have two ways to map them onto a given sized area of printed picture elements:

1) you can map the input image elements one-to-one to output printed picture elements and tell the output device to space the printed picture elements to fill the desired space.

In this case, each of the output elements faithfully represents a corresponding picture element of the original captured image. In the example given in my original post, the output elements would be spaced out to around 200 printed elements per inch.

-or-

2) you can tell the output device to print at a fixed number of printed picture elements per distance unit (pix per inch say) and then map the input picture elements to the output picture elements using some interpolation algorithm. If the number of original input picture elements are less than the number of output picture elements then the mapping is one-to-many. If the number of original input picture elements are greater than the number of output picture elements then the mapping is many-to-one.

Here, the output elements are an artificially created version of the original captured image and may or may not produce artifacts resulting from the transform algorithm.

Thus the question embedded in my original post is really asking whether the 'visual perception' of image fidelity/ quality is better using option (1) or option (2).


And yes, I know that there are other interpolation algorithms (arguably better) than the bi-cubic interpolation used in Paint Shop Pro -7 (PSP7), but that is beside the point of my question.
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Old Dec 29, 2002, 11:36 AM   #4
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Reply moved to correct thread here!

http://www.stevesforums.com/phpBB2/viewtopic.php?t=5871
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Old Dec 29, 2002, 11:57 AM   #5
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Looks like your reply somehow found its way into the wrong thread.
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Old Dec 29, 2002, 1:07 PM   #6
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Default whats up

:x :x hey jaws whats going on my man you ask for help and advice and then when someone out there takes the trouble to reply to try and help you ,you kick them in the nuts man,by replying with the knollage of a collage lecturer, im confused??,god bless :twisted: the uneducated!!
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Old Dec 29, 2002, 3:00 PM   #7
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Jaws is right so I'll take it away and put it somewhere else, no offence intended, nobody's perfect!
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Old Dec 29, 2002, 5:57 PM   #8
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Seems to me your question boils down to what does a better job of interpolation your software or your printer? Im not sure… but I choose the printer(adjust print res to get the print size you want) Some cropping will may be necessary). Try some test prints.
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Old Dec 30, 2002, 4:41 AM   #9
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Most people's printers 'interpolate' anyway because they rarely reproduce the dot size and density specified, on the paper they are using.

Look at a printout with a pocket microscope. If you see no white space between the dots your print setup is 'interpolating' i.e the ink dots are bleeding or you have 'dot wobble/weave' option set!
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Old Dec 30, 2002, 10:35 AM   #10
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hzxlvf, voxmagna-

Thank you very much for your replies.

I was hoping to avoid trial and error, but in my heart I figured that's what it would boil down to. <sigh>

This brings up a related question. Since ink jet type printers produce their picture elements as a group of dots of the CMYpCpM inks using some type of dithering process controlled by the printer's software, have people found that there are 'natural' or 'preferred' resolution settings that are better suited to the printer's dithering pattern.

My specific interest is relative to the Canon S900, but I'm also interested to know if there is a general answer to this that applies to a range of popular printers.

I was hoping to find that there are certain combinations of image resizing, printer resolution, printer interpolation, printer dither (magic ratios or some such) that yield the optimum printed image fidelity.

-*-*- by the way, please let me know if I should be posting this sort of question elsewhere (ink printer? software?) -*-*-

jeff
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