Megapixel to Print size questions and Fractal Print Pro curiosities...

Hi.

I am trying to squeeze larger, quality images out of a 6.1MP D100. I
have always had major disbelief for interpolation but Fractals Print
Pro is supposedly able to increase image res by 800% with little
degradation. In my tests I find that complete bull****. I am
wondering if anyone else uses this program and what they've found their
limits to be with this program.

Also another question regarding MP and printing. the 6.1MP D100
indicates that at 240ppi my "native" print size is about 8x12". I have
printed many prints at 16x20" at 300 dpi that have looked fine and I
could hardly tell the difference. It seems quite a stretch but i'm
wondering what my limit is where I truly lose control of the image?
Does the printer make a big difference by chance?

I have even printed 24x36" prints from a 6.1MP camera and they have
came out great. Granted, they were printed on Lambda 130C's and
Lightjet's... Both print at around 400ppi.

Thanks!

 

The Lambda and Lightjet may print at 400 ppi "BUT" if you do not have
enough original pixels to do so, you are still printing interpolated
data. A 24 x 36" image with 400ppi of information would require a 138
MPixel image!!!!!!!!. You had to do some very heavy duty interpolating
to go from 6.1 to 138 MP. A 24x36" print may require only 150-200 ppi to
look very good because you don't view it as close as you do a 4x6.
But even at that resolution, the image would have to contain at least
19.5 MP, a large but certainly more reasonable upsample from an original
6.1 MP image. To answer your original question.....

I don't think there is a Magic Number of original ppi required to make a
great print. Resampling degrades an image. More resampling degrades it
even more. Where the degradation becomes objectionable to YOU, only you
can answer. Image quality is a very subjective thing. What one person
may regard as great, another may regard as a POS.
Bicubic resampling in PS is actually pretty darn good and even though
the new pixels are invented out of thin air, they are invented in a very
logical and intelligent manner. I have no problem at all with most
images, resampling from 6 to 12 MP. YMMV.
Bob Williams

 

I may be misunderstanding you here. A 24x36 inch print at 400 ppi
requires 24x400 x 36x400 pixels = 138.24 MP.

Did you perhaps mean that you were printing a 6.1 MP image after
expanding it with the fractal program? Or perhaps you meant "dpi"
rather than "ppi" where "dpi" = ink drops per inch (with many ink drops
contributing to one pixel.) Or maybe you just meant that the
maximum resolution of the Lambda and Lightjet printers is about
400 ppi but the prints you made were at lower resolution.

As for how many pixels per inch you require, and how large a
print you can expect from a 6.1 MP camera, there are several
variables to consider:

1. How much detail is in the image?

Images with fine detail lose it when enlarged. Images without
fine detail or images that don't care about fine detail (e.g., many
portraits and landscapes), may enlarge a great deal before they
begin to look bad.

2. How far back will people stand when viewing the image?

An image that people will see from three feet away can be much
lower resolution than one meant to be viewed from one foot
away.

3. What do people expect to see?

Someone looking at a poster doesn't expect to see the detail
he might expect in a fine art print.

In short, the subject, the viewing conditions, and to some extent
the expectations of the audience, all affect the amount of
enlarging you can do with an image.

You might search Google for a message with the subject:

"3, 4, 5, 8 MP 8x10 printout comparison - Long"

for an analysis I did of 8x10 prints made from 3, 4, 5 and 8 MP
cameras.

I concluded in that posting that you could make an 8x10 print
from a 5 MP image that was virtually indistiguishable from an
8x10 made with any higher resolution camera. I'm sure that 8x12
from a 6 MP camera is also as good as any made from an 8,
10, or 100 MP camera. But, extrapolating from the results I saw,
even at 11x14, it would be possible to detect differences between
6 and 8 MP images with fine detail. Still, for many subjects and
viewing conditions, 24x36 might indeed look just as good from a
6 MP camera as from a higher resolution device.

Alan

 

You should be aware that most printer software 'manipulates' the image
to make a better print, and does so well. Mine will even straighten a
slightly slanted scan! It is sometimes difficult to get a good reading
on what dpi to print at when the printer software is 'active' in the
process.