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10-18-2009, 10:58 PM   #1
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DPI on K200D

Hello,
I have the K200D and i am always taking photos in RAW format.
In the RAW information the DPI is only 72x72 is there anyway of making it better (300DPI) or this is ok ?

Thank you in advanced,
Antonis Georgiou

10-18-2009, 11:23 PM   #2
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This is a commonly misunderstood topic, but see this thread from just a few days ago:

https://www.pentaxforums.com/forums/post-processing-printing-software-darkroo...-question.html

Bottom line: your image is not 72dpi just because the EXIF says it is. Your image is 3872 dots long, period. You can not* say how many dots per inch it is until you know how big you are printing it. And at that point, simply divide 3872 by the length of your print in inches - and that will tell you how many dots per inch your image is.

*EDITED - I originally left out the word "not" in the paragraph above!

Last edited by Marc Sabatella; 10-19-2009 at 08:59 AM.
10-19-2009, 08:49 AM   #3
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QuoteOriginally posted by anthger Quote
In the RAW information the DPI is only 72x72 is there anyway of making it better (300DPI) or this is ok ?
Marc's absolutely right that "resolution" is an oft-misunderstood topic. The only thing that really matters is the pixel *dimensions* of the file. Resolution in terms of dpi (or more correctly "ppi" or pixels per inch) only comes into play when you start discussing printing and/or viewing the image at a specific size.

Resolution in ppi is largely determined by the RAW convertor you use. In my own case of using Lightroom and ACR, I have the resolution fixed at 240 ppi because, based on my own judgement, that's the optimum resolution for a high-quality print....so by setting ACR's export preference for 240ppi, I know exactly what size print I'm able to produce at that resolution. If I want a larger print, I simply enter the dimensions I want (w/o interpolating the image) and what I get back is the final resolution in ppi at that print size...at that point I can decide if that ppi will result in a good-enough quality print for my purposes.

The reason for 72ppi generally has to do with displays....display resolution is typically 72-96ppi. As I'm looking at my EIZO CG211 which is 1600x1200 and roughly 17"x13"...and my MacBook Pro display which is 1440x900 and roughly 13"x8.25", I get about 92-94ppi and 110ppi respectively...so it would appear that 96ppi would be the more optimum "resolution" if all I were doing is displaying them on my monitor. I think the other reason for 72ppi is typography and the fact that Postscript is based on 72 "points" to the inch.


Regards,
Terry
04-20-2010, 11:22 AM   #4
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I tin you guys are bringing it out away from the original topic .
The question asked " is there anyway of making it better (300DPI) for k200d?"
because in my case , i m joining a competition which needed contestant to submit photo that is 300 dpi and above , which is recorded in the exif file on my photo , and it is fixed at 240 , is there anyway that i can change it to 300 dpi and above ?

regards
leonal

04-20-2010, 12:24 PM   #5
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Marc, thanks for the explanation.
04-20-2010, 12:34 PM   #6
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That *is* the original topic, and we didn't get away from it. A camera does not have a resolution in dpi. That's like asking what's the height of the Gettysburg address - it just can't be measured that way. *Prints* have meaningful DPI values; digital cameras and their images do not. You can't measure dpi - dots per inch - until you know how many inches you are printing. And since the camera doesn't have a resolution in dpi, there is no way to make it higher or lower. You can change the dpi of the *print* you make form the image, but you don't do that by fiddling with EXIF - you do it by making sure you have 300 times as many pixels as you intend to print in inches.

Read the responses again. An image is 300dpi if it has 300 times as many pixels as it will be printed in inches, period. A 4x6" print is 300dpi if it has 1200x1800 pixels, period. It does not matter what the EXIF says for this. There is nothing you can possibly put in the EXIF that would make 1200 divided by 4 not equal 300, so if you have 1200 pixels print in 4 inches, it is 300dpi, period, end of story. Similarly, an 8x12" print is 300dpi if it has 2400x3600 pixels, period. , end of story, regardless of the nukber in the EXIF, because there is nothing you could possibly put in the EXIF that would make 2400 divided by 8 not equal 300.

Now, if the people judging the competition for some strange reason don't care about the *actual* dpi of the image - pixels divided by inches, exactly as I explaiend above - but instead care only about the number in the EXIF, then the easiest way to do that without risking screwing up your image is to find an EXIF editor and change the number yourself. Trying to do this in Photoshop without already knowing *exactly* what you are doing is likely to result in altering the image, which you most definitely do not want. So I'd recommend a utility like ExifTool that you can trust to only change the number in the EXIF.
04-21-2010, 08:57 AM   #7
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Perhaps what the OP wants is something very practical.

Go into your image editor and find the image dimension settings. In Photoshop this is on the Image menu as "Image Size". At the bottom of the dialogue window, unclick "Resample Image". Then, type in the Resolution figure you wish, say "300". This will change the physical document size but not the number of pixels in width or height. Save and submit.

You can do the same in any other decent image editor, including many free ones.

Then, come back to read what Marc has said.
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