Preparing for Mpix - DPChallenge Forums

Nikon AF-S DX Zoom-Nikkor 18-55mm f/3.5-5.6 ED

12/11/2007 02:06:54 PM · #1

I have photos on a cd taken by someone else that are straight from the camera (JPGS).
I need to get them printed, I chose Mpix, vs something local.
The shots are from a 20d.
They are still at 72dpi.

Do I need to upscale them to 240 or 300dpi before uploaded to Mpix?
If so can I "batch" that someway?

I have PS2/Lightroom.

PS- I am just wondering about the DPI issue, not editing them.

Message edited by author 2007-12-11 14:07:21.

kandykarml

Nikon D80

12/11/2007 02:26:38 PM · #2

That's a good question.. I use Mpix for everything and I would suggest sending them this question.. They've answered questions from me before rather quickly, so it wasn't like I had to wait days for a response.

smurfguy

Canon EOS-5D Mark II

Canon EF 24-70mm f/2.8L USM

12/11/2007 02:30:22 PM · #3

Hi Tim,

Short Answer:

An image file does not have DPI or PPI. A file has only resolution: width x height pixels. So there's no reason to go through and do anything to the images. The size of your prints (and image file resolution) will determine the effective DPI.

Only a display medium has DPI/PPI - like your monitor or a printer.

More than you wanted to know: =)

For example, a typical monitor might display 100 pixels per inch (it varies, depending on screen resolution and monitor size), so an image of 640x480 px would show up as 6.4x4.8 inches on the screen.

A printer, with a native DPI of 300, would print the 640x480 image at 2.13x1.6 inches. However, as you know, you can print an image at any size you want. If I printed the 640x480 image as an 8x10" print, it would have an effective DPI of about 80, and it wouldn't look good.

Of course, viewing distance comes into play, but assuming a photo print that people view up close, I wouldn't print anything at less than ~150dpi. My Rebel XT has a resolution of 3456x2304. With my 150 DPI rule of thumb, I can make prints of up to 23x15 inches.

A 20D (assuming Large JPEG mode) has a resolution very similar to my XT.

Cheers,
-Jeff

Message edited by author 2007-12-11 14:31:11.

Nullix

Canon EOS-5D Mark III

Canon EF 17-40mm f/4.0L USM

12/11/2007 03:22:30 PM · #4

I'm not certain what PS2 is. There is PhotoShop CS2 around, but PhotoShop2 might've been only available running in DOS. I think I started with PhotoShop4 or 5.

I have a 20D also and you should easily get a 300dpi 4x6 image easily. You can also automate this by creating an action. Checkout my tutorial Creating Photoshop Actions.

I would first resample to 300dpi. In the menu, goto Image/Image Size. Uncheck "Resample Image" and change the resolution to 300ppi.

To crop, I use the "Fit Image" automation. This way if it's a landscape or portrait orentation doesn't matter. In the menu, goto File/Automate/Fit Image and use 1800 width and 1800 height. This will make the longest side 1800.

Good Luck

12/11/2007 03:32:19 PM · #5

I meant cs2-- twas a typo--

Canon EF 24-70mm f/2.8L USM

12/11/2007 03:40:00 PM · #6

OKay this is from Mpixs website---

Recommended file size

Digital Cameras measure their resolution in pixels. These pixels are NOT measured per inch, but are a total count of how many pixels were used to capture the entire image. If you take a digital photo at 1600x1200 pixels, the total pixel count of the captured image will be 1,920,000 pixels. Whether you print this 1600x1200 image as a 8â��x10â�� photo or an 16â��x20â�� photo, it will still have 1,920,000 pixels.

Photos intended for print should be taken at the highest [pixel] resolution possible for the best print quality. Printing at different sizes does not change how many pixels are in the original image. Lower resolution photos printed at larger sizes stretch the pixels beyond the point where they look clear and sharp. The best printer can not make a low resolution photo look better than its original qualityâ�¦ but it sure can make beautiful prints when given a high resolution photo to work with!

Then in the FAQ-- the have this..

FAQs
What DPI is optimal?
250 dpi is recommended.

smurfguy

Canon EOS-5D Mark II

12/11/2007 04:07:46 PM · #7

Originally posted by MPIX site:

Digital Cameras measure their resolution in pixels. These pixels are NOT measured per inch, but are a total count of how many pixels were used to capture the entire image. If you take a digital photo at 1600x1200 pixels, the total pixel count of the captured image will be 1,920,000 pixels. Whether you print this 1600x1200 image as a 8â��x10â�� photo or an 16â��x20â�� photo, it will still have 1,920,000 pixels.

Photos intended for print should be taken at the highest [pixel] resolution possible for the best print quality. Printing at different sizes does not change how many pixels are in the original image. Lower resolution photos printed at larger sizes stretch the pixels beyond the point where they look clear and sharp. The best printer can not make a low resolution photo look better than its original qualityâ�¦ but it sure can make beautiful prints when given a high resolution photo to work with!

That sounds an awful lot like my post above...

Originally posted by buzzrock:

What DPI is optimal?
250 dpi is recommended.

Ah, so my rule of thumb was 150, theirs is 250. So they would suggest that I print my XT images at no larger than 13x9.2".

...

Or, if you're really in the mood to create an action to go through and lossily resize all your images, go for it.

...

Oops - bit my tongue a little too late. Apologies for the snarkiness.

12/14/2007 05:54:47 PM · #8

Got my piccs back today-- and MPIX does have really good quality, blows away walmart/sams club..

One mistake made though was in the wallets. You have to allow for more room on top then you think- dont crop tight-- reason is, the wallets peel off, so you lose some of the picture when peeling-- hence I lost some hair on very tight crops---- cheap enuf, I'm gonna reorder more wallets, w/ different crops..