Image quality and print size issues

[trichardlin]

Ok, I've been reading this site since 1999 and this is only my first post. After reading the Canon SD800 IS review, I felt that I have to bring up the issue of print size and see what people think.

When talked about image noise and showing the night scene at different ISO settings, the article stated:

"You start seeing a loss in detail right away -- at ISO 100. Still, a small to midsize print is still very possible. At ISO 200 there's a more noticeable smudging of details, limiting your print sizes to 4 x 6 or so."

A 7mp image is limited to print size of 4x6? Hmmm. OK, let's see.

I downloaded the image at ISO 80 and ISO 400 (not 200), set both images to 240 dpi in PS CS2 (no resizing) and printed them from my Epson R2400 using Epson's Enhanced Matt paper. The printer settings were: enhanced matt, best photo, and let Photoshop manage the color profile. Since I didn't want to waste too much ink on all that black background, I cropped both images down to the center 3x4 inches where the details are. Guess what? At normal viewing distance (about 15 inches) the two images were really not that different. Sure they are different, but I was printing at 12" x 9", not 4 x 6.

This exercise led me to think, in real life printing, we really don't need that many pixels, and, dare I say, we might not even need super high quality pixels. Half of the game is in Photoshop and in printing (color management proper printer settings, paper selection, etc) anyway. I also think reviewers in general should probably spend less time splitting pixels on screen, and spend more time printing. Also, reasonable print size should be suggested, not prints that are meant to be examined with a microscope.

I'm also curious to know what kind of mileage one can squeeze out of their image. I once had a 5 mp image (from a Sony W1) printed up to 24" x 31" and it looked quite nice at a normal viewing distance of about 3-4 ft. This was after up-sampling in Photoshop a bit. Has anyone printed really large prints from low mega-pixel images?

Richard

[Razr]

Ok, I've been reading this site since 1999 and this is only my first post. After reading the Canon SD800 IS review, I felt that I have to bring up the issue of print size and see what people think.
(SNIP) of some really intersting conclusions.
When talked about image noise and showing the night scene at different ISO settings, the article stated:
"You start seeing a loss in detail right away -- at ISO 100. Still, a small to midsize print is still very possible. At ISO 200 there's a more noticeable smudging of details, limiting your print sizes to 4 x 6 or so."

I'm also curious to know what kind of mileage one can squeeze out of their image. I once had a 5 mp image (from a Sony W1) printed up to 24" x 31" and it looked quite nice at a normal viewing distance of about 3-4 ft. This was after up-sampling in Photoshop a bit. Has anyone printed really large prints from low mega-pixel images?
My question is:
is there a commonly agreed upon "normal viewing distance" scale-chart for 4x6? 8x10? 11x14? 20x24?
Where is that commonly agreed upon scale located?
And what reliable source determined the distances?

I aks because four feet is certainly too close to a 24 x 31 print to call if "normal viewing distance". Four feet is too close for a 16 x 20.

[mattdm]

This excersie led me to think, in real life printing, we really don't need that many pixels, and, dare I say, we might not even need super high quality pixels. Half of the game is in Photoshop and in printing (color management proper printer settings, paper selection, etc) anyway. I also think reviewers in general should probably spend less time splitting pixels on screen, and spend more time printing. Also, reasonable print size should be suggested, not prints that are meant to be examined with a microscope.

This assumes your goal is prints. I only print out pictures to send to my grandma. The primary target is on-screen viewing.

This may lead one to believe: okay, then really, you only need the image to look good at 1280x960, or 1600x1200 at best.

But, I'm not just taking pictures to be looked at now. I want my kids to be able to look at these pictures when they're old and be happy with them. Consider that 800x600 was a pretty normal screen resolution ten years ago. Many people were still running 640x480. I don't think it's at all unreasonable to expect a typical computer screen to be 30 megapixels in 50 years.

A 30mpix camera is, um, a bit out of my price range today. But, since I *am* comparison shopping, I do appreciate both the overview and the detailed pixel-peeking in reviews.

[trichardlin]

My question is:
is there a commonly agreed upon "normal viewing distance" scale-chart for 4x6? 8x10? 11x14? 20x24?
Where is that commonly agreed upon scale located?
And what reliable source determined the distances?

I ask because four feet is certainly too close to a 24 x 31 print to call if "normal viewing distance". Four feet is too close for a 16 x 20.

Good point. Four feet may indeed be too close for 24x36. You can call that 'close examination' distance probably. My feeling is, a normal viewing distance for anything from 4x6 to 8x10 is probably the distance that one would use when reading a book. For larger prints, the distance would be a few feet, like one would use in a gallery or a museum. Any closer, the museum staff may start to get nervous. :)

It's obviously important for Jeff to point out noise issues in his reviews. I just thought that the statement about print size is a bit misleading and seems unfair for what the camera is capable of. My guess is, at iso 400 in low light, the images produced by SD800 can be perfectly printed to 11x14, or even larger. But readers of this article might think they can only print to 4x6 at iso 200. To Jeff's credit, he does encourage readers to download these images and print them out.

-Richard

[trichardlin]

This assumes your goal is prints. I only print out pictures to send to my grandma. The primary target is on-screen viewing.

Well, the original comment was about printing. The review article recommended that at iso 200, the image can only be printed at 4 x 6, which I didn't agree.

No doubt more pixels are better and higher quality pixels are better, but I also think you can print a very decent 8 x 10 picture with just a 3 mp image.

-Richard

[mattdm]

No doubt more pixels are better and higher quality pixels are better, but I also think you can print a very decent 8 x 10 picture with just a 3 mp image.


True. I actually have some 2MP images which I'm perfectly happy with as 8x10s. That's still 150ppi, after all -- way better than almost any computer monitor at this point.