Resolution and Printing size????

[rickp1]

I ahve a friend that has some images on photobucket that where converted from RAW to JPG before uploaded. Now the image resolutions are 72dpi. She wants the images to be 300dpi so she can print them at a size 4x6. Does she really need to change the images to 300dpi or will the current resolution print good 4x6 images? Also what is the max size she will be able to print with the 72dpi?

Thanks

R.

[Barbara V]

I'm glad you asked this question; I've been wondering about dpi re: printing size myself.

[RichardTaylor]

What are the image sizes in pixels?

for 300 "DPI" a 6x4 print needs (6x300)x(4x300) or 1800x1200 pixels.

[rickp1]

it's 1023x682 at 72ppi

R.

[RichardTaylor]

Forget the 72 PPI

Without resizing the picture in software and wanting to print at 300 "DPI"

She can print at 1023/300 x 682/300 or 3.4" x2.2"

However just print them out as they are and you will probably find they are reasonable. You don't always need 300 "DPI".

[rickp1]

Richard,
I printed one of the images and told her just that. The images looked good enough for what she was doing with them.

Let me ask you. Is there a standard for the minimum resolution an image should be for good quality results?

[RichardTaylor]

I am just a hobbyst so I can't give you a definitive answer.

This page may help.

Image Resolution and Print Quality - How Image Resolution Affects Print Quality - Photoshop Tutorial

I just print my own pics, either approx A4 (~11x8") or 5x7", on my home printer and they look good.
I use a Canon 350D (Rebel XT), 40D & 5D

Even pics that I have uploaded to the web, usually around 1280x 1024 pixels, still look great when resized to 240 pixels/inch,printed as 10x8, and viewed at normal distances (arms length). In a seniors camera group I am in they are amazed at how good they look. Admittedly I am the only one processing & printing my own pics. They are taking the memory cards straight out of their P&S cameras and having them printed at stores like "Wal Mart" .

[dcclark]

I've typed it a hundred times in a dozen threads, but:

Images do not have an inherent DPI, and

The "DPI" setting stored with your images means nothing for most printing purposes!

DPI is determined by 2 things:

1. How many pixels are in the image, and
2. The physical print dimensions (i.e. 4x6, 8x10, etc.)

If you take the width of your image (in pixels) and divide by the width of the print (in inches), you'll get the number of dots per printed inch. That's DPI, no matter if the file claims 72dpi or 300 dpi.

Your friend who wants 300 dpi: why? There's nothing magic about it. I happily print 4x6's at 200 dpi, and 24x36's at 120dpi. They both look great, because you view them at different distances.

My recommendation is just to print the largest file you can (in pixel count) at whatever size you want. With modern cameras, it's almost guaranteed to be more than enough pixels to look smooth and nice.

[rickp1]

thanks guys, great info. Once again I leave this site learning something.

R.

[teaking]

All I will add is that when printing its blobs of ink not square pixels and todays printers can do a lot with lower resolution files so I agree dont become obsessed with DPI or PPI.