image size for printing

[tomsphotography1664882219]

<p>I shoot with a 40d and a 17-55 f2.8<br>

My image is of a group (4persons full lenght) wedding scene at 12.3mp CR2 RAW, this reads as 3888x2592. I then crop to 1998x2497.<br>

Using lightroom 3 I then convert to jpeg for printing and i am now left with a file of only 2.53mp<br>

In LR3 i leave the image quality as 100% at 320ppi.<br>

I am concerned that I have started with a file of 12.3mp and now left with only 2.53mp for printing. Is this right or am i going wrong somewhere?<br>

For printing i use photobox.<br>

What is the biggest size high quality print I could expect from this and am I doing anything wrong in the process to get the final print size?</p>

<p>Thanks<br>

Tom</p>

[mark_sirota1]

<p>Do you really mean MP (megapixels) or MB (megabytes)? If you mean megabytes, don't worry about it.</p>

<p>Exporting to JPEG in Lightroom shouldn't affect the number of megapixels, unless you check the "Resize to Fit" checkbox in the Export dialog. (You should do this -- set the dimensions to the size you want to print.)</p>

[tomsphotography1664882219]

<p>Mark you're right, sorry I meant MB megabytes not MP, my thought process was that from a 12.3 mb file to a final one of 2.5mb seems considerably smaller. Whilst I am aware that i have both cropped and compressed it to a JPEG, I was curious as to the image quality that would be produced by such a small sized file in terms of MB or is there no corelation here at all?<br>

from a 2.5mb file size in jpeg what size picture with high to good image quality could i make?</p>

[mark_sirota1]

<p>For JPEGs, file size doesn't really tell you anything about how big you can print. A 100% JPEG is very nearly equivalent in quality to an 8-bit TIFF.</p>

[mukul_dube]

<p>Divide pixel size by 300 to get inch size. Many print at much lower resolution, like 200 ppi. Your 1998x2497 should comfortably give you an 8" by 10" or even larger.</p>

[brad_smith8]

<p>On my Epson 2880 using the same camera and (amazing) lens (or a 70-300) with the same pixel dimensions (full frame), I print via Qimage which reports a 13x19 print at about 205ppi (3888/19), and the prints are as sharp as a tack.</p>

<p>I print from PSD's or TIFF's.</p>