Optimal Resolution for Print size

[JMM]

My lab sent me an optimal resolution for print size chart. I do not understand this.
Take up to 5x7. Long edge 1500, DPI 215, File size 4.6 MB.
Take an image processed thru Canon software at 350 DPI
PSP shows 2912 x4368 350 DPI. When I crop to a 5x7 using the crop tool it shows 2715x3802 with a resolution of 543. Do I need to spend more time resizing the photo to 215 DPI? Does this not reduce the quality of the 12 MP camera that I spend tons of money for?

Also, if I want to take that already cropped 5x7 and give a low resolution image to a senior for web posting, should I change the print size & resolution or Pixel dimensions and to what???????

Thanks,
Joyce

[danchez]

what it sounds like, you need to crop it to a 5x7 format and set your dpi to 215, then resize the long side to 1500 pixels. I think. Hopefully someone will have a more definitive answer for you.

[JMM]

It also does not make sense. The chart says the file size should be 4.6 MB. After cropping to 5x7, resizing to 215 dpi, 1076x1506, file size shows only 235 KB. Am I doing something wrong?

[ldelacruz]

These are just recommendations and not exacts. Crop to 5 x 7 and change the dpi to 215. For print don't worry about the long edge 1500 or the 4.6mb. Sharpen after the crop.

My 5x7's are closer to 1.2mb at 240 dpi and this is from a 21mp, 25mb file.

Also, what is PSP?

[JMM]

That is just another step which takes more time. I have only been cropping and leaving dpi alone. Does not seem to affect the print. Will they be better if I change the dpi. Seems to defete the purpuse of 12MP.

Corell Paint Shop Pro XI

[ldelacruz]

It most likely won't make it better but the file size would be smaller and easier to email. Most printers ask for 240 or 300dpi. My printer recommends 240. I am not familiar with PSP but in Photoshop you can set your cropping parameters to do it in one step.

It has nothing to do with megapixels.

[JMM]

I see. Trying to learn everything and make sure I am doing everything to make the best possible print.

Your recommendation for web size prints? 75 dpi for a 4x6print? Will that do?

[ldelacruz]

I use 72 for the web only and 240 for prints.

[JMM]

When I change the resolution to 72 dpi for web size, should I also change where it shows print size? Does that matter?

[ldelacruz]

Use 2 different files. 1 for the web and 1 for print.

The web image should not be longer than about 800 pixels wide by 600 pixels high for landscape and about 600 pixels high by 400 pixels wide for portrait. This way it will fit on most monitors. The dimensions are not an exact but just a guide.

[JMM]

Thanks for the help. I understand it a little better.

Joyce