Photo Resolution

[RallyHippy]

So I am toying with the idea of making a poster and everything is pretty good except the main picture may not have the resolution to do a good one.

For printing how little resolution would be acceptable? 150, 200, 300, more?

I understand the higher the better but a 4"x6" poster is not nearly as fun as say a 24"x18"

With a 24"x18" size project the photo has 137x138 dpi...

[WhiteKnucklePhotog]

300 dpi is what a lot of pre-press departments do their work flow at, so that is a good rule of thumb. I've also heard that you can "legally" double the resolution in Photoshop, say from 137 to 274, without losing any quality. I've done this plenty of times and "got away with it." haha

A good test would be to make a 5x7 at walgreens, one at 137, and one at 274, of a cropped area of your poster, something with a lot of detail and color range. Then you'll know fo sho

[RallyHippy]

Ok i have heard good and bad things about the resolution "uppers" and that is a good idea to print them out and see what happens i didnt even think about that.

[Morison]

A theoretical minimum resolution is 1.5x the screen resolution that the printer is using (assuming offset printing)
MOST shops will run 155 line screen for this type of project, high quality is about 200. Therefore ... you'd want 230-300 dpi.
I HAVE gotten away with matching the line screen for some projects and I have successfully up-sampled an and the image look not too bad.
Upsampling is best done incrementally, increasing by about 10% a step.

If you're doing a 'photo' poster - it'll fall apart (visually) when you look closely at it, but posters are usually viewed with a bit of distance anyway :-)

[ashleyedwin]

I am a photographer by profession and I am using Epson printer for this. And it also work perfect for me. But few days I am looking that the photo copies are coming hazy and a massage is coming like epson error 0x69 . I am not able to fix it out.