Print resolution vs image size

Am I better off reducing the resolution of an image to get the required size for printing, or increasing the image size to maintain a high resolution ? When I first started digital work I scanned my slides and sent them off for printing. The companies I used recommended a resolution of 300ppi, so I reduced the size of my images to suit. When I bought a printer I continued to reduce the size of my images to obtain the correct print size at 300ppi. I've been happy with the quality so never had reason to challenge the figure of 300ppi. However, now that I am using a digital camera the images need to be enlarged to achieve the print sizes I want at 300ppi. So, my question is, am I better off enlarging the image to get the required dimensions at 300ppi, or should I reduce the resolution of the image to obtain the required print size ? By way of example, suppose I have an image which is 2500 x 3750 pixels, and I want to print it 10 x 15 inches. Is it better to resize to 3000 x 4500 px and print at 300ppi, or to leave it as is and print at 250ppi ? Don't know whether it makes any difference but I use an Epson R1800 printer.

Am I better off reducing the resolution of an image to get the required size for printing, or increasing the image size to maintain a high resolution ?

When I first started digital work I scanned my slides and sent them off for printing. The companies I used recommended a resolution of 300ppi, so I reduced the size of my images to suit. When I bought a printer I continued to reduce the size of my images to obtain the correct print size at 300ppi. I've been happy with the quality so never had reason to challenge the figure of 300ppi.

However, now that I am using a digital camera the images need to be enlarged to achieve the print sizes I want at 300ppi. So, my question is, am I better off enlarging the image to get the required dimensions at 300ppi, or should I reduce the resolution of the image to obtain the required print size ?

By way of example, suppose I have an image which is 2500 x 3750 pixels, and I want to print it 10 x 15 inches. Is it better to resize to 3000 x 4500 px and print at 300ppi, or to leave it as is and print at 250ppi ?

Don't know whether it makes any difference but I use an Epson R1800 printer.

John I find it best to re-size the image so it is 300dpi at the eventual print size. I do everything on the image prior to re-size except sharpening. I sharpen the image at this print stage.

John I find it best to re-size the image so it is 300dpi at the eventual print size. I do everything on the image prior to re-size except sharpening. I sharpen the image at this print stage.

John, Printing at 250 ppi will be indistinguishable from 300ppi in a 10 x 15 print, in fact 150ppi would do the job. If I was printing this I would just leave it as it is. The printer will be printing at what - 2880dpi? Why do unnecessary work on the original? Roger

John,
Printing at 250 ppi will be indistinguishable from 300ppi in a 10 x 15 print, in fact 150ppi would do the job. If I was printing this I would just leave it as it is. The printer will be printing at what - 2880dpi? Why do unnecessary work on the original?

Roger

I have in the past got away with printing at 120dpi and nobody noticed; it was for a camera club contest. Professionally I print as high as possible/practical. 300dpi seems to be the accepted industry standard above which the human eye wouldn't be able to tell the difference; a low dpi may well be noticed in a wide expanse of colour like a sky, my very low dpi image was of a woodland where you can hide lots of errors. Why not try and see what is acceptable? Peter.

I have in the past got away with printing at 120dpi and nobody noticed; it was for a camera club contest. Professionally I print as high as possible/practical.

300dpi seems to be the accepted industry standard above which the human eye wouldn't be able to tell the difference; a low dpi may well be noticed in a wide expanse of colour like a sky, my very low dpi image was of a woodland where you can hide lots of errors.

Why not try and see what is acceptable?

Peter.

How are you going to resize the image? If you've only got say 3000 x 2500 pixels then how do you get more?

How are you going to resize the image? If you've only got say 3000 x 2500 pixels then how do you get more?

Thanks for the responses so far. John (Strawman) - that's the sequence of steps that I follow too. Roger - yes, the difference between 250 and 300 is probably tiny, though it would be useful to know at what point I am better off resizing the image rather than accepting the lower resolution. I guess you are suggesting that the answer is between 250 and 150 ppi. By the way, the printer claims "up to 5760 dpi", but dpi and ppi are very different things, so I'm not sure that helps much. Peter - I may have to try it and see. I just hoped that I may get an answer without using lots of paper and ink ! Ian (Westers) - in the same way that I resize an image to reduce it for upload to ePz, I would resize an image that I want to make larger. Except that I use bicubic when enlarging. Does anyone else have any insight to offer ?

Thanks for the responses so far.

John (Strawman) - that's the sequence of steps that I follow too.

Roger - yes, the difference between 250 and 300 is probably tiny, though it would be useful to know at what point I am better off resizing the image rather than accepting the lower resolution. I guess you are suggesting that the answer is between 250 and 150 ppi.

By the way, the printer claims "up to 5760 dpi", but dpi and ppi are very different things, so I'm not sure that helps much.

Peter - I may have to try it and see. I just hoped that I may get an answer without using lots of paper and ink !

Ian (Westers) - in the same way that I resize an image to reduce it for upload to ePz, I would resize an image that I want to make larger. Except that I use bicubic when enlarging.

Does anyone else have any insight to offer ?