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Photography Question 
Charley Andrisano
 

Prints, from a 4.51MB file


To Whom it May Concern: I have a 4.51MB JPEG file, and I want to make a 12x18 print from that file. Is this file large enough to give me sufficient detail in the enlargement? This file is going to a lab that does my enlargements, and they are very professional.

Thank you,
Charley Andrisano


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8/18/2008 5:00:56 PM

 
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  Megapixel Print Chart
Megapixel Print Chart
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Hi Charley,

what is "sufficient detail" for you? You won't get a 12x18 print of true photo quality (300dpi). But 'true photo quality' is viewed at a distance of between 12" and 18". Depending on the viewing distance being greater you can get away with a lower dpi.

Have a look at the megapixel chart.

Have fun!


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8/18/2008 10:53:13 PM

 
Charley Andrisano   Thank you Mr. Smith for your input, and the chart. Much appreciated.
Charley


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8/19/2008 7:07:27 AM

 
John P. Sandstedt
BetterPhoto Member Since: 8/8/2001
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  While I enjoyed looking at Willard's chart, the fact is I have made a great 13X19 print starting from an image file made with a Dimage 1 [3.1 MP sensor.]

The issue is not necessarily pixels [though they help.] The issue is data. My Canon 30D, with its 8.2 MP sensor gives me a 3.5 MB JPEG file. But, when I edit a file, I usually wind up with an 8X12, 24 MB TIFF file as my printing starting point.

Check out Shutterbug Magazine - a couple of issues back. There the question was answered with regard to what file size [sensor starting point, that is, megapixels] was acceptable to Stock Agencies. Not surprising to me - the answer was a minimum of 6 MP. The hype to get all the way to Canon's 17.7 MP in the 1Ds Mark III is just that, marketing hype.


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8/20/2008 1:06:19 PM

 
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"a great 13X19 print" is subjective, John.


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8/20/2008 2:08:41 PM

 
John P. Sandstedt
BetterPhoto Member Since: 8/8/2001
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  Any great print is subjective. But, when the one I'm speaking about wins a competition, I'd say it's pretty darn good.

Now, it wasn't my image. But, I played with it and increased the file size very slowly and carefully. File size also increases with almost any editing one does, so long as one doesn't knowingly delete pixels, as in cropping.

And, of course, I'mm sure you are aware of the available software [can't think of the program's name] designed to allow image size to be increased outside of Photoshop's Resampling algorithm.

In any event, my recommendation to friends is "no less than 6 MP," unless the use is solely for a computer screen [e-mail, web sites, etc.] In such cases, the 72 ppi resolution of the monitor is controlling.

But, you knew that . . .


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8/20/2008 2:20:03 PM

 
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Here's an image that was printed at a gorgeous, even breathtaking 13x24". At a lowly 150dpi! That is of course far from true photo quality. So it demonstrates that true photo quality is irrelevant with THIS particular image. It therefore demonstrates that it is VERY dependant on the image what is and is not possible. Or necessary.


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8/20/2008 2:50:32 PM

 
John P. Sandstedt
BetterPhoto Member Since: 8/8/2001
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  Will -

Besides the fact that dpi ain't the same as ppi, I guess I don't see your point.

As to a 13X24 print, the issue has nothing to do with ppi or dpi. One views a print of that size from a farther distance and therefore the resolution can be lessened.

According to a thread, which included a response by Jon Canfield, and one of his articles in Shutterbug . . .
Using an Epson printer one should send an image to said printer with a resolution of 350 ppi for prints smaller than 8X12. One may use lower resolutions, to as low as 150 ppi, for large prints. The reason - they are normally viewed from greater distances and, accordingly, the human eyes fails to "see" deficiencies. [Note, Jon indicated that 300 ppi should be used for Canon and HP printers.]

This fact was demonstrated in a competition at my Camera Club, in which a 12X18 print was presented. As one of the people handling the prints at the print box, the fact that the image was out of focus was obvious close up. But, from 12 feet or more, it was fine. When I pointed the issue out to the maker, he checked his file and agreed completely.

But, and to the point - 150 dpi is not the same as 150 ppi. Dots per inch refers to the amount of ink applied by the printer at a pixel. But, again, you knew that . . .


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8/20/2008 6:44:28 PM

 
John P. Sandstedt
BetterPhoto Member Since: 8/8/2001
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  Will -

Besides the fact that dpi ain't the same as ppi, I guess I don't see your point.

As to a 13X24 print, the issue has nothing to do with ppi or dpi. One views a print of that size from a farther distance and therefore the resolution can be lessened.

According to a thread, which included a response by Jon Canfield, and one of his articles in Shutterbug . . .
Using an Epson printer one should send an image to said printer with a resolution of 350 ppi for prints smaller than 8X12. One may use lower resolutions, to as low as 150 ppi, for large prints. The reason - they are normally viewed from greater distances and, accordingly, the human eyes fails to "see" deficiencies. [Note, Jon indicated that 300 ppi should be used for Canon and HP printers.]

This fact was demonstrated in a competition at my Camera Club, in which a 12X18 print was presented. As one of the people handling the prints at the print box, the fact that the image was out of focus was obvious close up. But, from 12 feet or more, it was fine. When I pointed the issue out to the maker, he checked his file and agreed completely.

But, and to the point - 150 dpi is not the same as 150 ppi. Dots per inch refers to the amount of ink applied by the printer at a pixel. But, again, you knew that . . .


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8/20/2008 6:52:23 PM

 
Ken Smith
BetterPhoto Member Since: 6/11/2005
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  Charley, I have the older style Digtal Rebel as a back-up...it's 6 Megapixels and I got a great blow-up at 20x30 inches. Is it perfect? I guess that's up to the individual. If you have a Sams Club nearby...you can probably afford to sink $12 into a 20x30 inch photo and see what it looks like. You can also do some Photoshop Image Size increases, at 110%, to enlarge the pixel size. Scott Kelby's books detail how to do this. Bottom line..you should be able to get a decent 12x18 shot...just take it in to the photo print place and give it a shot!


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8/20/2008 8:01:33 PM

 
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"I don't see your point"

John, the point is that some images like the above don't need "true photo quality" to look fantastic at very large print sizes.


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8/21/2008 1:06:40 AM

 
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