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Author Topic: Need to export 300 dpi with a long edge of 12 inches  (Read 5112 times)

Jglaser757

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Need to export 300 dpi with a long edge of 12 inches
« on: January 21, 2015, 09:12:43 am »

I have a request from company for printing,,

They want: JPEG 300dpi at about 12 incehs on longest side.

and not 300 PPI,

I have consistently done this wrong when exporting,,and have resorted to Raw files in the past,,

What are the settings..I thought it was 300 PPI,but every time I do, I get 72 DPI.
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Simon Garrett

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #1 on: January 21, 2015, 09:20:02 am »

If it's like the print companies I've sometimes used, they may need you to set 300dpi (set that in the "pixels per inch" box in the export dialogue - yes I know it's ppi but they probably mean the same thing) and also export to a resolution that gives 12 x 300 on the long side.  That is, set the long side to 3,600 pixels.  Some print machines are a bit funny like that: they need the number of pixels to be right (as they don't scale the image) but also for some perverse reason expect the PPI setting in the file to be right. 
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PhotoEcosse

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #2 on: January 21, 2015, 11:05:57 am »

I have a request from company for printing,,

They want: JPEG 300dpi at about 12 incehs on longest side.



Looks like your printing company is suffering from one of the commonest delusions promulgated by the mass of misinformation on the internet.

A Jpeg file can have neither a parameter of "dpi" nor a measurement in inches.

All it can have is a resolution expressed as width x height in pixels (e.g. 1600 x 1100 pixels). How that translates into inches on a screen depends entirely upon the resolution and the physical size of the screen. For example, the example I have just given would measure quite different dimensions in inches if displayed on a 21" monitor or a 27" monitor, even if both were set at 2048 x 1152 resolution. Similarly, when sent as a file for printing, the dpi at which it is printed bears no direct relation to the pixel dimensions of the file (although the file must contain sufficient data to "feed" the printer driver at the specified print settings).
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Slobodan Blagojevic

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #3 on: January 21, 2015, 11:13:24 am »

Simple, as Simon says: 12 x 300 = 3600. Set the long side to 3600 pixels in LR export dialog box.

Simon Garrett

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #4 on: January 21, 2015, 11:23:32 am »

Simple, as Simon says: 12 x 300 = 3600. Set the long side to 3600 pixels in LR export dialog box.

However, it may also matter what resolution you set in terms of dpi or ppi.

This is because some Fuji print machines don't scale the image, and simply print an image that is in inches 300 times the number of pixels. 

However, thse Fuji machines also look at the ppi setting in the file.  Goodness only knows why, but they throw a wobbly if the ppi setting in the file isn't right. 

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Slobodan Blagojevic

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #5 on: January 21, 2015, 01:29:24 pm »

Ok, never had that particular issue, so never paid attention to that box, but you are right. That way you are telling the printer what size the print should be (i.e., 3600 / 300 = 12 inches)
« Last Edit: January 21, 2015, 04:41:00 pm by Slobodan Blagojevic »
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digitaldog

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #6 on: January 21, 2015, 03:36:05 pm »

They want: JPEG 300dpi at about 12 incehs on longest side.
and not 300 PPI,
Confusion here. Digital images are made of pixels so when you speak of their resolution, it IS PPI. An output device creates dots, that's DPI.

You are referring to what is a resolution tag and it's rather meaningless. It could be 72PPI or 180PPI but it doesn't have an inherent meaning, only what you could produce with the number of pixels you have at your disposal. Work with pixels! For example, let us say you have 1000x1000 pixels to keep the math simple. And to simplify this further, let's only consider the horizontal axis. If you have 1000 pixels and divide that by 72, that is, you provide 72 pixels per inch, you could end up with 13.8 inches using that division (1000/72=13.8). Let's now say you divide up your 1000 pixels using 180 instead. 1000/180=5.5. In both cases, you had 1000 total pixels. The document itself doesn't have a size, other than what space it takes up on your hard drive. The sizes above are examples of what could be produced if you divided up the total number of pixels you have, with some number of which is just a tag within the document. In Photoshop, if you use the Image Size dialog, turn resample OFF (do not allow it to create more or remove pixels), you can enter any value, 72, 180, 1000 into the resolution field and the resulting size is calculated for you. But you haven’t changed the document or the data at all. You just changed a theoretical 'size' if you output your 1000 pixels using that resolution. So again, it's meaningless until you output the data. At that point, lets say you print the image, you can decide how big you wish it to appear and/or how many pixels you want to devote to the output. You have 1000 pixels and someone tells you that you must use 300DPI (which isn't true but that's a different story). 1000/300 would produce a 3.3 inch print. You want a bigger print? Lower the DPI (within reason). You set the DPI for output to use 180 of your pixels to produce 180DPI? You get a 5.5 inch print (1000/180=5.5).

Work with pixels. That's a fixed attribute of the data unless of course you resample that data (add or remove pixels).
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Wayne Fox

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #7 on: January 21, 2015, 03:38:41 pm »

However, it may also matter what resolution you set in terms of dpi or ppi.

This is because some Fuji print machines don't scale the image, and simply print an image that is in inches 300 times the number of pixels.  

However, thse Fuji machines also look at the ppi setting in the file.  Goodness only knows why, but they throw a wobbly if the ppi setting in the file isn't right.  


There are a few machines out there that do it, Noritusu may do it as well.  My chromira looks at the document dimensions and will scale the image accordingly, so if I send it a 3000x2400 pixel file which should give me an 8x10, but it’s set to 100 PPI in the metadata, it uses that to determine the desired document size and then will scale it - much like any inkjet printer would do. I guess they are trying to honor the document dimensions.

So despite the fact that if you have resized the image to the right pixel dimension it should be irrelevant (as has been pointed out by others), it does need to be set correctly.

From Lightroom, export the image from the file menu, in image sizing option chose resize to fit, select Long Edge from the pop up, set the size to be 12 inches (or whatever) and set the Resolution to be 300 PPI. (a little differently but with the same result as Slobodan)
« Last Edit: January 21, 2015, 03:41:12 pm by Wayne Fox »
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Slobodan Blagojevic

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #8 on: January 21, 2015, 04:55:56 pm »

I have a request from company for printing,,

They want: JPEG 300dpi at about 12 incehs on longest side....

Come to think of it, you are lucky, they gave you two necessary parameters (so you can calculate the third, or as Wayne pointed out, let the program calculate it). The beef I have with some magazines is that they will simply tell you "send us a 300 dpi file," assuming that you are familiar with their magazine dimensions. If i have them laying around, I can measure it, if not.. tough luck. And what if they like it so much they want to print it double-spread? You would think that magazines should know better, but it is most likely some poor intern tasked with correspondence behind it.

eliedinur

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Re: Need to export 300 dpi with a long edge of 12 inches
« Reply #9 on: January 22, 2015, 04:16:51 am »

Ok, never had that particular issue, so never paid attention to that box, but you are right. That way you are telling the printer what size the print should be (i.e., 3600 / 300 = 12 inches)
So despite the fact that if you have resized the image to the right pixel dimension it should be irrelevant (as has been pointed out by others), it does need to be set correctly.

There is also another reason to take the time when exporting from LR to set the proper number in the ppi box. Jeff Schewe has indicated in the past -
http://www.luminous-landscape.com/forum/index.php?topic=66916.0
that the adaptive adjustments made by the built-in PK Output Sharpening are influenced by the ppi flag which tells it whether to optimize for a low resolution display medium (screen) or a high resolution print.
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