# Question re: resolution in Plug-in edits



## Gene_mtl (Aug 30, 2013)

Using LR5.2 RC with both NIK & onOne Perfect Photo Suite plug-ins.

When we send an image out to the plug in, LR asks a number of questions such as file type (PSD, TIFF, etc), Colour space (ProPhotoRGB, Adobe RGB 1998), etc) and _*Resolution*_.

I shoot with an old Canon 5D. Images are 4368x2912 as shot. I seldom crop smaller than 3840x2560 or 320ppi (or as close as to that as LR's crappy crop tool will allow).  

Is there an ideal value one should use when LR asks for that resolution?  Does it really matter since you are sending out an image of 'X' pixels by 'Y' pixels and the image is being returned at the same dimensions?  And if the number is important, what would the optimum value be without having to calculate the actual ppi of an image each and every time? 

TIA.


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## DaveS (Aug 30, 2013)

The resolution thing that Lightroom asks is a ppi number. Which really has nothing to do with the price of tea in China.    All it tells you, is how big the picture will be in inches if you print it at that resolution.   It has nothing to do with crop or pixel sizes (the X and Y thing you mention).  So the basic value of 300 is a nice rule of thumb for printing.


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## clee01l (Aug 30, 2013)

Gene_mtl said:


> ...I seldom crop smaller than 3840x2560 or 320ppi ...


 You only crop pixels. Pixels are unitless until displayed.  PPI optional fields in the EXIF AFAIK, no modern printer uses this field. It is unimportant what you put in this field. If you leave the field blank the EXIF standard defaults to 72 

If you print on paper, you instruct the printer how to fill up the page with your pixels. The printer driver will translate and interpolate the pixels in your image to a fixed dot density of the printer.  Any pixel density between 180 and 300 is usually acceptable. More than 300 is overkill. I have printed 30"X24" prints at a density of 110ppi and have a fine image hanging on my wall.
If you display your image on your monitor at 1:1 resolution, it will display at something between 96 and 120 ppi no matter what value is in that field.  If you do the same on a HiDPI (Retina) display the resolution is always fixed at around ~240ppi


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## Gene_mtl (Aug 30, 2013)

Thanks, guys,

Cletus: I do not print locally but rather through commercial labs such as SmugMug (rarely because of associated shipping costs to Canada) or Costco(.ca).  Recently I was checking the cost of a print on canvas at 20x30 inches and uploaded a file that was 3840x2560 pixels  I was informed that the file was too small for that size print.  Mind you I can not find what they consider the minimum resolution.

I have onOne's Perfect Resize 7.5. I could possibly use it to up-size the image.  But suspect I need to find out what they require


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## clee01l (Aug 30, 2013)

Perfect Resize is a solution when you don't have enough pixels.  I suspect that some commercial operations may even use it.  

I think there are no hard fast rules although 180ppi is a pretty good one.  Here is a link to Walmart's mimimum photo resolution page.  Note that the Walmart minimum for 20"X30" is 2100x1400 pixels or 70ppi.   Keep in mind that 20"X30" is going to be viewed a a farther distance than an 8X10.

http://photos2.walmart.com/walmart/helpphotoresolution

The people that printed my photo as a gallery wrapped canvas offer free shipping.  They don't specify if this includes Canada but you can check. 
http://www.gallerydirect.com/


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## Gene_mtl (Aug 30, 2013)

For years I'd heard of Genuine Fractals, now known as Perfect Resize, but did not realize I had it.   From what I've read, it is an impressive bit of software.

Again, thanks Cletus.  I'll check out your link for more details, but I did see they charge shipping to Canada depending on where in Canada.  So that will add to costs.


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## Jim Wilde (Aug 31, 2013)

Although I don't use it very often, I've heard good reports of Lightroom's own up-sizing capability.


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