Enlarging a photo

[Huntin]

I want to send a file in to an online store to be enlarged. I use photoshop 7.0 for my editing and shoot a canon 20D on large file size. I was wondering if when sending in my file, should I leave it the size it was origionally taken or use "image size" in photoshop to adjust the photo to the size that I want. Also, I know that dpi is a printer setting, but does it matter what resolution I save and send the file to them?

 

[The_Traveler]

yes,
crop it to the aspect ratio you want (4x5, 4x6 etc.)
then upsize the image

[ame]http://www.youtube.com/watch?v=qu5adJfxuhw[/ame]

 

[gmarquez]

I've had my images printed by both Kodak and MPix, and for both I only made sure that the aspect ratio of my image files matched the aspect ratio of the prints I wanted. For instance, to get a 30"x20" print, I made sure that the image I sent was 3/2 as wide as it was tall.

Different photo processing labs have different requirements (setting DPI, etc.), however, with the labs I've used, I've ONLY had to make sure that the aspect ratio was correct.

As far as resizing the image, I think that professional labs that "print" to photo paper (Kodak Endura, Kodak Metallic, Fuji Crystal Archive, FujiFlex, etc.) all have hardware+software boxes called RIPs (Raster Image Processor) that do a much better job at upsampling the image than you can do yourself.

 

[EOS_JD]

If you look in photoshop's image size pop up, you'll see no mention of dpi. You are correct in stating this is a figure relating to the number of dots your printer will output the image at.

In the image size pop up, the term ppi (pixels per inch) is used and this is very important when determining the quality of your image output. (Your image is made up of pixels)

Your 20D produces an image size of 3504 pixels by 2336 pixels. The image size can actually be anything you like but the larger the size the lower the ppi setting will be.

Print Size = No of pixels / resolution (ppi)
Resolution (ppi) = No of pixels / print Size
No of Pixels = Print size x resolution

You should be able to work out what you require from one of the equations above.

For images larger than A4, you can print at resolutions lower than 300ppi. I print my A3+ images (19" x 13") at 180ppi and if you look at the print from a normal viewing distance yu would not see any difference from an image printed 6x4 @300ppi!

Let me know what you are looking to do and I'll help if I can.

Regards
Jim