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I took a couple of images on a 3.2 mp camera (Minolta Xt) at the highest
quality setting (fine) and the largest file size. Then I cropped and
enlarged what I wanted (just a dirt bike going over a jump with nothing buy
clear blue sky), then saved the file. The saved file was only about 150k
and the original was about 1.2 mb. I did not enlarge too much, but the
resulting photo was somewhat on the grainy side, compared to the full photo
with all the extra detail. Some graininess was to be expected due to the
enlarging, but not too objectionable for what I was doing--just goofing
around. So, after cropping and enlarging, should I expect such a smaller
file? What is the best way to keep the image "crisp" when enlarging--if
there is one?

BTW--it seems that my 2.1 mp camera (Oly C700UZ) with its nice optical zoom,
takes better far away shots than the 3.2 mp Minolta Xt--but I have not had a
real opportunity to compare fairly. The Xt on close up photos (across a
table or room) seem really nice!

--
Rudy Marcelletti, K8SWD

> I took a couple of images on a 3.2 mp camera (Minolta Xt) at the highest
> quality setting (fine) and the largest file size. Then I cropped and
> enlarged what I wanted (just a dirt bike going over a jump with nothing
buy
> clear blue sky), then saved the file. The saved file was only about 150k
> and the original was about 1.2 mb. I did not enlarge too much, but the
> resulting photo was somewhat on the grainy side, compared to the full
photo
> with all the extra detail. Some graininess was to be expected due to the
> enlarging, but not too objectionable for what I was doing--just goofing
> around. So, after cropping and enlarging, should I expect such a smaller
> file? What is the best way to keep the image "crisp" when enlarging--if
> there is one?
>

Cropping and enlarging will always reduce quality. An example: if you crop
that 3.2 Mp picture to 1/3 of its original width and height, you end up
with a 0.35 Mpixel image - which is surely grainy. The file sizes you
mention indicate about that amount of cropping. The same thing happens if
you use digital zoom for filling the frame. Optical zoom is usually better
than cropping and enlarging.

The file sizes also depend on the JPEG quality level you use. Many programs,
such as the freeware Irfanview that I use, allow you to set different JPEG
quality levels. The file size may vary as much as 5x depending on the
quality level, for the same number of pixels.

Just my $0.02
Nils

"John M" <> wrote
> A 150k jpg will generally create a pretty lousy print - even at 4x6

Not true at all. It will produce a good 4x6 or even a 5x7 just fine.
Resolution is more important than compression, anyway. A 150k jpeg at a
normal compression level might be a 1024x768 or 1280x960 image. That's
plenty big enough to print at 4x6 or perhaps 5x7.

Depends on how much you cropped. File (memory) size is NOT a good
representation of the resolution of a file. Instead, after cropping
recheck the horizontal and vertical pixels. The product of the two
tells how many pixels are left. It is PIXELS, not kilobites of memory,
that establish resolution.

Another thing to do is keep track when you say you ENLARGED it. Did you
resample (add pixels)? If so, by how much. Resampling with good
algorithms can give maybe a forty or even fifty percent increase and
still be useful. However, doubling the (linear) resolution is usually
beyond practical limits.

"Rudy Marcelletti, K8SWD" wrote:
>
> I took a couple of images on a 3.2 mp camera (Minolta Xt) at the highest
> quality setting (fine) and the largest file size. Then I cropped and
> enlarged what I wanted (just a dirt bike going over a jump with nothing buy
> clear blue sky), then saved the file. The saved file was only about 150k
> and the original was about 1.2 mb. I did not enlarge too much, but the
> resulting photo was somewhat on the grainy side, compared to the full photo
> with all the extra detail. Some graininess was to be expected due to the
> enlarging, but not too objectionable for what I was doing--just goofing
> around. So, after cropping and enlarging, should I expect such a smaller
> file? What is the best way to keep the image "crisp" when enlarging--if
> there is one?
>
> BTW--it seems that my 2.1 mp camera (Oly C700UZ) with its nice optical zoom,
> takes better far away shots than the 3.2 mp Minolta Xt--but I have not had a
> real opportunity to compare fairly. The Xt on close up photos (across a
> table or room) seem really nice!
>
> --
> Rudy Marcelletti, K8SWD

--
Don Stauffer in Minnesota

webpage- http://www.usfamily.net/web/stauffer