Printing of Poster

[blueblood]

I have a friend who would like to use some of my photographs to print into poster of about 24"x30" for an event. I'm not sure if the quality of my photographs are good enough for it. The dimensions are about 5200x3740 and 4910x7360, and pixels are between 1.5MB to 3.8MB. What are the criteria that I should be looking into ? Are they sufficient to print into poster?

Trying searching out, but didn't get answers that I need. Thanks for your advice.

 

[Edwin Francis]

From the info you provided, yes.

The file size (MB) hardly matters. Take your pixel size divided by the print size in inches. For e.g. 5200/30 = 170 dpi.

170 dpi may be low for a fine art print, but should be good enough for a poster. In my ad agency days, we did prepress work to 200 - 300dpi for print ads, 100 - 200dpi for posters/banners.
You may want to upsample to reduce jaggies, esp if there are straight lines close to 0° or 90°

Caveat: This does not take into account other issues - density, banding etc. Your printer should be able to advise you on that.

 

[blueblood]

Appreciate for your explanation. I guess that since the photographs are already taken, there is no way to increase the pixel size. You can only do it from the camera setting. it is good to know that the pixel size of 150-170 dpi can produce decent posters. Will get the advice from the printer.

 

[catchlights]

Appreciate for your explanation. I guess that since the photographs are already taken, there is no way to increase the pixel size. You can only do it from the camera setting. it is good to know that the pixel size of 150-170 dpi can produce decent posters. Will get the advice from the printer.

FYI, quality of the image is referring to the composition, colour accuracy, sharpness etc, there is little to do with physical file size, for an example, from a same RAW image if you over sharpen and export it, it will increase the file size dramatically, so does it mean image with a bigger file size has better quality?

btw, no one view a poster print at a close up distance, so a lower dpi is perfectly acceptable.
you can interpolate your images, just to prevent pixelation during printing, but will not add in any more details to the image.

 

[DSolZ]

For bigger prints you can go for a lower dpi since big prints means larger viewing distance. There should be some article around online taht recommends the dpi for various print size

 

[blueblood]

Thank you for seniors to explain and provide the information. The relationship of the dpi, pixels and distance will take me sometime to understand and digest in the different print out.