Printing to poster size (20 x 30)

[Rory Tate]

I believe someone mentioned an inexpensive site that printed 20x30 posters for around $10. If not, can y'all recommend a vendor who does produce acceptable posters from a digital file?

At that size (20x30) what's the lowest dpi the image should be set at for a reasonably clear poster?

If the image is saved as a jpg, will agressive compression badly harm the final printout?

Currently, my image is at 180 dpi, and is imaged out to 20 x 30. The file size is about 5 megs uncompressed, and about 380 K compressed to the max.

This image is of great sentimental value to a lot of people so your help will be much appreciated.

Rory Tate

[Scottes]

For 20x30 then 180dpi is good, since that size probably won't be viewed too closely. You'll want higher DPI if people are going to look closely, and you could go down a little more if people aren't going to be very close at all. But if it's 20x30 now at 180 DPI I'd leave it alone.

Aggressive JPGing will harm the file, though it probably won't be seen too much at normal viewing distance for this size. However, the image quality will be lessened due to 180 DPI - and I'm assuming that you upsized it some - so why make it any worse? I would save as maximum JPG quality unless something completely prevents you from transferring a 5 MB file.

[Rory Tate]

Thanks, Ninja

The image came out of the camera (10D) at 180. Thanks for your advice. I'll send it in at 5 megs.

Rory

[robertwgross]

Thanks, Ninja

The image came out of the camera (10D) at 180. Thanks for your advice. I'll send it in at 5 megs.

Rory

The DPI tag placed on that image in the camera means nothing, absolutely nothing, because there is no physical dimension associated with it. When the file comes out of the camera it is roughly 3000x2000 pixels, period.

Once you get it into your editing program, you can resample up or down, and you can set dimensions for a print. For 8x10 prints, 300 DPI is good. For something bigger like a poster print, 200 DPI is plenty good enough.

---Bob Gross---

[Scottes]

The image came out of the camera (10D) at 180. Thanks for your advice. I'll send it in at 5 megs.

If it's a 10D image then 3000x2000 is only 100 DPI for 20x30. This will not do, IMHO. 10x15 is much more reasonable, and some could even argue for 8x12 giving you 250 DPI.

To get 20x30 as it is now, it had better be damned sharp and hopefully it won't be viewed very slosely at all. You may want to upsize it and clean it a bit, unless the printing copany can do that.

[robertwgross]

To get 20x30 as it is now, it had better be damned sharp and hopefully it won't be viewed very slosely at all. You may want to upsize it and clean it a bit, unless the printing copany can do that.

By "upsize it", he means to resample it to a larger file size, but with the same print dimensions.

We know what we mean!

---Bob Gross---

[htbyron]

Remember too that the lab may use a high-quality RIP (which I think stands for Rasterized Image Processor) program, which will likely do a better job upsizing than PS (or even QImage). So you might check with them to see what they recommend. I sent ELColor my original file (after cropping & image correction, of course), without up-rezing, & they did a nice job printing using their own software.

Good luck,
Tom

[Scottes]

A RIP is used to convert vector-based (like EPS) to raster-based (like TIFF). It inherently won't do a better job, and may do a worse job.

However, a RIP is generally pretty well tuned to the printer, so it will know how to resize an raster graphic for that printer, and will usually do a very respectable job.

However, you won't know that until you've tried it. And even then you won't know until you compare your upsize technique to the RIP's upsize technique by getting two prints done.


If you know what you're doing, do it and don't let anything (like a RIP) run automatically on your stuff.

If you don't know what you're doing, don't really care, or aren't concerned with the differences, then let the printer upsize your image (whether a RIP or not).

I don't think that any automatic printer-based or RIP-based software will do a better job of upsizing than a human with skill and intelligence and a technique suited to the image type. However, it may take a pretty goood eye to tell the difference because it may be quite slight.