FAQ: enlargements & printing your photos

It might not get stickied but it could be linked to in the sticky FAQ Read first thread.

It is already - you didn't read it did you?

Tim,
Thanks for the tip on printing 8 x 10. I was going mad trying to size an 8 x 10 (kept going to 6.xx),and printed on Ilford paper no less.

Wonderful write up. I'm sending a few photos to the printer for the first time, and this has helped tremendously. Thank you.

Onto another topic though, can you recommend a printer in Oz? I've been looking into Digital Works in Melbourne. They seem pretty good, and have been recommended by a few others.

deletedpenguin wrote in post #4293027
Onto another topic though, can you recommend a printer in Oz? I've been looking into Digital Works in Melbourne. They seem pretty good, and have been recommended by a few others.

Happy to have helped I use Nulab in Melbourne for some of my orders, even though i'm in New Zealand, they're great.

Tim I can understand how the quality of a print shops software and printer are able to produce larger photos from lower resolution files. But how does that affect printing at home with a standard inkjet printer?

I ran a test using a jpeg large/fine image and a Canon IP4300 printer.

I opened the file and resized the image to ?x8" at 72 ppi using bicubic smoother. Then cropped the image down to 10" x 8" still at 72ppi and printed the image.

I reopened the file and resized the image to ?x8" at 300ppi using bicubic smoother . Then cropped the image down to 10" x 8" still at 300ppi and printed the image.

The difference between the two photos is dramatic. Even my little 4300 printer, which is a good printer but not even close to the best, gives a warning if you try to print anything at less than 220 ppi.

Do we need to treat the files differently depending on whether it will be printed from a home based inkjet or by a print shop? Or does it still not matter?

You misunderstood my original post. The number of pixels is what matters, not the ppi. In your 72ppi image (assuming it was 12x8) you had 864 x 576 pixels = 0.5 megapixels. With 12x8 at 300ppi you had 3600 x 2400 pixels = 8.6 megapixels. That's why your prints look so different. If you simply change the ppi value without resampling the image (ie turn off the resample checkbox in the image size dialog) then print them 8x12 the images will look identical.

Tim, I have a question I haven't seen asked before: why?

Why is that 72 dpi (not ppi, usually) in there anyway? Is it really part of the EXIF?

I don't see it in the shots from my DSLR, as viewed by Exifer or FastStone. FastStone does show print size at 180 PPI, though.

It looks to me that editing software inserts the 72 dpi or ppi figure.

BTW, 72 PPI is about what you'd see on a 19" monitor (14" horizontal) viewing at 1024 X 768.

So where does that pesky 72 figure come from, and why?

Enquiring minds want to know!

-js

I guess 72ppi is because Canon decided they should set it to something rather than leave it empty. It's irrelevant. I don't shoot JPG so i've never looked at what it does, I set the PPI in my RAW converter. 72 is the traditional value that PC screens use I think.

72dpi is there because that is the standard for web browsers...

JNeumann54 wrote in post #4415054
72dpi is there because that is the standard for web browsers...

Actually I believe it is the standard for monitors, specifically most LCDs (although some montiors use 96 PPI).

But really it does not matter. Here is some great info as well:

Say no to 72 dpi

But is that number really in the EXIF from the camera? I don't see it with any of my photo viewing programs.

Here's the EXIF from a recent shot, direct from the camera, as shown by Canon File Viewer Utility:
File Name
IMG_4916.JPG
Camera Model Name
Canon EOS DIGITAL REBEL
Shooting Date/Time
11/22/2007 6:06:52 PM
Shooting Mode
Aperture-Priority AE
Tv( Shutter Speed )
1/200
Av( Aperture Value )
8.0
Metering Mode
Evaluative
Exposure Compensation
0
ISO Speed
800
Lens
18.0 - 55.0 mm
Focal Length
55.0 mm
Image Size
3072x2048
Image Quality
Fine
Flash
On
Flash Type
External E-TTL
Flash Exposure Compensation
0
Red-eye Reduction
Off
Shutter curtain sync
1st-curtain sync
White Balance
Auto
AF Mode
One-Shot AF
Parameters
Contrast +1
Sharpness +1
Color saturation +1
Color tone Normal
Color Space
sRGB
File Size
3214KB
Drive Mode
Continuous shooting
Owner's Name
Strappe
Camera Body No.
1360435739

So I guess the 72 PPI is inserted by Photoshop. Yes? No?

-js

I guess so, yes.
Note that by default, ACR sets resolution to 240ppi.

Hermeto wrote in post #4418454
So I guess the 72 PPI is inserted by Photoshop. Yes? No?

I guess so, yes.
Note that by default, ACR sets resolution to 240ppi.

I'm not so sure. This got my curiousity going so I examined the Exif in several programs; DPP, Breeze Browser, Opanda IExif and Dalifer Lite, an Exif reading utility. The results were varied.
1. RAW files: DPP and BB showed nothing about resolution. Dalifer showed different things for the 40D and the 350D. For both cameras it showed the sensor resolution (4438.65 on x axis, 4445.97 on y for the 40D). For the 350 it also showed X Resolution - 72 and Y resolution - 72 for both the main image and the embedded jpg thumbnail. For the 40D it showed X Resolution - 72 and Y resolution - 72 for the embedded jpg only. Opanda does not read RAW
2. Jpgs from the camera: DPP, BB and Dalifer as above, except that for the 40D as well as the 350D Dalifer shows 72 for both the main and the thumbnail images. Opanda shows "X Resolution - 72, Y Resolution - 72", both cameras.
3. Embedded jpg extracted from the RAW by BB: DPP and BB show no resolution figure. Dalifer and Opanda show 240 (!?). The number was apparently changed by BB.

I HAVE TOO MUCH FREE TIME.

In2Photos wrote in post #4415085
Actually I believe it is the standard for monitors, specifically most LCDs (although some montiors use 96 PPI).

From what I have read, it was the standard for TV screens back in the '60s when the EXif standard was first formulated. I don't think it applies to either CRT or LCD monitors.