File size for 300dpi

<p>Reuters have a rule for submitted images that requests a maximum of 300 DPI.<br>

What file size in Mb would that be equivalent to? Any tips?<br>

I have heard that it equates to "Jpeg Small" from say Nikon or Canon.</p>

<p>File size is determined by number of pixels, color depths and generaly and by file format, but not by the single file parameter value that describes how to print the file (DPI), or how the picture was scanned.</p>

<p>DPI is just a single data item recorded in the file placeholder, and does not affect the filesize.</p>

<p>For DPI to be useful you also need to know the picture size, and from DPI and Inches of size, you could compute the number of pixels by multiplying DPI by the size value, in each direction of the picture, then multiply those to get total pixels. Then knowing number of pixels you could possibly try to estimate what file size it could be.</p>

<p>As you can see you can have a very small or a very big file size, all attached with the attribute DPI=300. It is up to you.<br>

E.g. at 300 DPI, and 10 x 15 inches required size you will have (300x10 ) by (300 x 15) pixels.<br>

This will give you 3000 by 4500 pixel size, or about 13.5 Mpixels. <br>

For this requirement you will need a camera with13.5 MPixels, if native pixels are required.<br>

You could possibly obtain more pixels from lower resolution camera by interpolation, or "upsizing", if that is allowed by Reuters.<br>

Find out more about Reuters requirements.</p>

<p>Think of DPI like you would miles per gallon. You can talk about car efficiency by saying a car gets 35 mpg, but you have no idea how long a trip you can take until you know how big the gas tank is. Same thing with DPI. That's a reference to how many pixels are crammed into a given inch of image ... but doesn't tell us anything about how many inches of image they actually want (and that, in turn, tells us something about how large the resulting file will be). You need to know actual image dimensions, in pixels, or you need to know DPI <em>and</em> the number of inches wide/tall.</p>

<p>Shadforth,<br>

Here is why pixel count is important: these two images are both 13k in size, display onscreen as 1" and are 72 pixels × 72 pixels. You would think that they are the exact same. They are, but...</p>

<p><img src="http://www.domaschuk.com/MiscImages/1.jpg" alt="" /> <img src="http://www.domaschuk.com/MiscImages/2.jpg" alt="" /></p>

<p>However, one is 72 DPI and the other is 14,000 DPI. Online it doesn't make a difference. However, if you go to print them, one of them will print at 1"×1" (72 pixels at 72 DPI) while the other will print at 0.00514" (72 pixels at 14,000 DPI)</p>

<p> </p>

<p>Referring back to their requirements, they are silent on the actual file size that results from 300 DPI resolution.<br>

I looked at their guidelines a couple of years ago and they have loosened up quite a bit since then by now allowing some limited post processing so long as it does not change the nature or characteristics of the image.<br>

<a href="http://handbook.reuters.com/index.php/A_Brief_Guide_to_Standards%2C_Photoshop_and_Captions">http://handbook.reuters.com/index.php/A_Brief_Guide_to_Standards%2C_Photoshop_and_Captions</a><br>

Thanks for the comments</p>

<p>Forget the file size. It's <em>dimensions</em> you need to know about.</p>