Image size , A technical puzzle.

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

One of the images was a bit over 500 k. The other was over twice the size.

The size of the second image exceeded the size limit for the
competition, so I saved at as a slightly lower quality, to comply with
the size limit.

Why would there be such a large a difference?

The only thing I can thinnk of is that the smaller image was cropped a
bit more than the larger.


--
PeterN

In article , PeterN
wrote:

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

there is no ppi in a jpeg file.

there is a tag that *suggests* an initial size, such as for a page
layout app (and that tag may not necessarily be used, depending on the
app), but other than that, the tag is meaningless.

ppi only matters when printing.

anyone who requests a jpeg file at a specific ppi has no clue.

the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.

One of the images was a bit over 500 k. The other was over twice the size.

different compression levels and/or different amount of detail.

The size of the second image exceeded the size limit for the
competition, so I saved at as a slightly lower quality, to comply with
the size limit.

why is there a file size limit at all? especially for small images such
as 1024x768.

are they running this on an ancient computer with a tiny hard drive
such that they don't have enough space for all the entries?

a file size limit makes no sense and only motivates people to save in a
lower quality with more artifacts. why do they want people to submit
****ty looking photos??

contests like these are run my morons. the answer is to not participate
and optionally try to educate them.

Why would there be such a large a difference?

see above.

The only thing I can thinnk of is that the smaller image was cropped a
bit more than the larger.

you said they both have the same pixel dimensions.

whether one had been cropped or not makes no difference. the computer
has no way to know.

On 2015-07-10 03:09:56 +0000, nospam said:

In article , PeterN
wrote:

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

there is no ppi in a jpeg file.

Only in the resolution for setting dimensions with pixels/

there is a tag that *suggests* an initial size, such as for a page
layout app (and that tag may not necessarily be used, depending on the
app), but other than that, the tag is meaningless.

ppi only matters when printing.

Actually there DPI matters.

anyone who requests a jpeg file at a specific ppi has no clue.

There I agree.

the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.

....and the final size of the image given in pixel dimensions is
meaningless without a corresponding resolution set as PPI.

For example the given 1024 x 768 @ 100ppi resolution would result in a
10.24" x 7.68" image. Using the same pixel dimensions @ 300ppi would
produce a 3.41" x 2.56" image.

One of the images was a bit over 500 k. The other was over twice the size.

different compression levels and/or different amount of detail.

The size of the second image exceeded the size limit for the
competition, so I saved at as a slightly lower quality, to comply with
the size limit.

why is there a file size limit at all? especially for small images such
as 1024x768.

Yup! Again I find myself agreeing.

are they running this on an ancient computer with a tiny hard drive
such that they don't have enough space for all the entries?

a file size limit makes no sense and only motivates people to save in a
lower quality with more artifacts. why do they want people to submit
****ty looking photos??

Agreed. It seems to be an odd competition that requires poor quality
image files.

contests like these are run my morons. the answer is to not participate
and optionally try to educate them.

I think education would be more productive, unless they are competition
tyrants.

Why would there be such a large a difference?

see above.

The only thing I can thinnk of is that the smaller image was cropped a
bit more than the larger.

you said they both have the same pixel dimensions.

whether one had been cropped or not makes no difference. the computer
has no way to know.

That was my thinking.

--
Regards,

Savageduck

In article 2015070920462718676-savageduck1@REMOVESPAMmecom,
Savageduck wrote:

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

there is no ppi in a jpeg file.

Only in the resolution for setting dimensions with pixels/

it's meaningless

there is a tag that *suggests* an initial size, such as for a page
layout app (and that tag may not necessarily be used, depending on the
app), but other than that, the tag is meaningless.

ppi only matters when printing.

Actually there DPI matters.

ppi, not dpi.

dpi is a function of the printer.
ppi is how big a print will be for a given pixel dimension.

anyone who requests a jpeg file at a specific ppi has no clue.

There I agree.

the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.

...and the final size of the image given in pixel dimensions is
meaningless without a corresponding resolution set as PPI.

For example the given 1024 x 768 @ 100ppi resolution would result in a
10.24" x 7.68" image. Using the same pixel dimensions @ 300ppi would
produce a 3.41" x 2.56" image.

only if it's printed. otherwise ppi means nothing.

set the ppi tag to whatever you want. the number of pixels remains the
same and the size on your display remains the same.

One of the images was a bit over 500 k. The other was over twice the size.

different compression levels and/or different amount of detail.

The size of the second image exceeded the size limit for the
competition, so I saved at as a slightly lower quality, to comply with
the size limit.

why is there a file size limit at all? especially for small images such
as 1024x768.

Yup! Again I find myself agreeing.

are they running this on an ancient computer with a tiny hard drive
such that they don't have enough space for all the entries?

a file size limit makes no sense and only motivates people to save in a
lower quality with more artifacts. why do they want people to submit
****ty looking photos??

Agreed. It seems to be an odd competition that requires poor quality
image files.

poorer than it needs to be.

they should be requesting maximum quality jpeg, not limiting it.

contests like these are run my morons. the answer is to not participate
and optionally try to educate them.

I think education would be more productive, unless they are competition
tyrants.

based on his description of the requirements, they're so clueless that
it likely won't be very productive.

another option is try to educate the other contestants.

Why would there be such a large a difference?

see above.

The only thing I can thinnk of is that the smaller image was cropped a
bit more than the larger.

you said they both have the same pixel dimensions.

whether one had been cropped or not makes no difference. the computer
has no way to know.

That was my thinking.

yep.

In article 2015070920462718676-savageduck1@REMOVESPAMmecom,
Savageduck wrote:

are they running this on an ancient computer with a tiny hard drive
such that they don't have enough space for all the entries?

a file size limit makes no sense and only motivates people to save in a
lower quality with more artifacts. why do they want people to submit
****ty looking photos??

Agreed. It seems to be an odd competition that requires poor quality
image files.

contests like these are run my morons. the answer is to not participate
and optionally try to educate them.

I think education would be more productive, unless they are competition
tyrants.

looks like the latter.

since peter has mentioned neccc, it appears that this is the contest:

http://neccc14.neccc.org/2015_conf/P...ition-Rules_20
15.pdf

with the actual entry form here, which has its own set of issues:
http://www.greaterlynnphoto.org/members_entry00.php?request=neccc

note the requirements:
Digital images: The equipment used for judging this competition uses
1024 X 768.

what **** equipment is that?? have they not heard of hd projectors?
1920x1024 pixels is common now, and people frequently use them with a
home theater setup.

Horizontals must have a width of 1024 or smaller; verticals must have
a height of 768 or smaller.

i guess they don't like portrait orientation. assuming a 4:3 aspect
ratio, that would end up being 768x576. the description says resizing
might set it to 511, which is a 2:3 ratio (versus 4:3).

a 511x768 pixel entry? seriously?? are they kidding?

d. Square composition images are acceptable as long as they fit into
this 1024 X 768 window.

why not just say square images must be 768x768 or smaller?

f. Resolution should be 100. Winning images are reproduced in the
NECCC Bulletin and therefore need the large resolution size.

resolution should be 100 what? pixels per inch? pixels per centimeter?
miles per hour? have they heard of units?

not only that, but resolution is not something that is referred to as
having a 'size' and 100 (assuming they mean ppi) is certainly not very
high especially if it's going to be printed. 1024x768 would be suitable
for about 3-4 inches.

if they 'need the large resolution size' for their bulletin, then why
are they limiting entries to 1024x768? they could run a script to
downsize the images for their ****ty projector, while keeping the
larger originals for publication.

plus, anyone doing page layout for the bulletin would presumably know
how to resize it to fit whatever layout they want, which will change
the ppi anyway.

the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.

Maybe this is not the case, but there can be reasons to ask such a
resolution, I can think about web-only view (no need for print) and
low-rate internet audience (not everyone in the world have Gbit
internet as default) as some of those reasons.
--
andrea - ri mi cci, name

On 7/9/2015 11:09 PM, nospam wrote:
In article , PeterN
wrote:

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

there is no ppi in a jpeg file.

there is a tag that *suggests* an initial size, such as for a page
layout app (and that tag may not necessarily be used, depending on the
app), but other than that, the tag is meaningless.

ppi only matters when printing.

Yes. They intend to print certain images.



anyone who requests a jpeg file at a specific ppi has no clue.

See above.


the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.


That may be true, but that is not my issue. One of the images was 500k
and the other a tad over 1 mb.
One of the images was a bit over 500 k. The other was over twice the size.

different compression levels and/or different amount of detail.


Originally they were both saved at the same level of compression. I had
to lower the compression level for the other to conform. Why, is my
question.

The size of the second image exceeded the size limit for the
competition, so I saved at as a slightly lower quality, to comply with
the size limit.

why is there a file size limit at all? especially for small images such
as 1024x768.

are they running this on an ancient computer with a tiny hard drive
such that they don't have enough space for all the entries?

a file size limit makes no sense and only motivates people to save in a
lower quality with more artifacts. why do they want people to submit
****ty looking photos??

contests like these are run my morons. the answer is to not participate
and optionally try to educate them.

That may be true, but doesn't answer my question. Which is again, why
should I have to lower the quality.


Why would there be such a large a difference?

see above.


I said they were saved at the same compression level.

The only thing I can thinnk of is that the smaller image was cropped a
bit more than the larger.

you said they both have the same pixel dimensions.

whether one had been cropped or not makes no difference. the computer
has no way to know.

That's what I thought. I mentioned that to provide all information.



--
PeterN

In article , PeterN
wrote:

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

there is no ppi in a jpeg file.

there is a tag that *suggests* an initial size, such as for a page
layout app (and that tag may not necessarily be used, depending on the
app), but other than that, the tag is meaningless.

ppi only matters when printing.

Yes. They intend to print certain images.

not very big if the source is 1024x768.

that's about 2x3" or so at 300 ppi, possibly 3x4" if they want to
accept a little lower quality (250 ppi).

anyone who requests a jpeg file at a specific ppi has no clue.

See above.

the tag doesn't matter. period.

the tag might be used to set an *initial* print size (or object size in
a layout app), but that's about it. that size can be changed at any
time, which will change the ppi, regardless of what the tag specifies.
most of the time, the tag is ignored.

if they're expecting to get an 8x10 out of it (which is what 100 ppi
would do), it's going to look like garbage because 100 ppi is *really*
low for printing. ideally it should be 250-300 ppi, depending on
intended viewing distance of the print.

the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.

That may be true, but that is not my issue. One of the images was 500k
and the other a tad over 1 mb.

it is your issue since you're participating in a competition run by
idiots who do not know what they're doing.

One of the images was a bit over 500 k. The other was over twice the size.

different compression levels and/or different amount of detail.

Originally they were both saved at the same level of compression. I had
to lower the compression level for the other to conform. Why, is my
question.

as i said, there are two factors. if compression is the same for both,
then the other factor is what will affect the size, that being detail.

in other words, one image has more detail than the other, whether it's
real detail or sharpening artifacts.

On Fri, 10 Jul 2015 08:05:40 -0400, PeterN
wrote:

On 7/9/2015 11:09 PM, nospam wrote:
In article , PeterN
wrote:

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

there is no ppi in a jpeg file.

there is a tag that *suggests* an initial size, such as for a page
layout app (and that tag may not necessarily be used, depending on the
app), but other than that, the tag is meaningless.

ppi only matters when printing.

Yes. They intend to print certain images.

But the 72ppi they require fit no printer but that was the common ppi
of CRT screens.



anyone who requests a jpeg file at a specific ppi has no clue.

See above.


the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.

See rule 22.
--

Regards,

Eric Stevens

On 7/10/2015 6:49 PM, Eric Stevens wrote:
On Fri, 10 Jul 2015 08:05:40 -0400, PeterN
wrote:

On 7/9/2015 11:09 PM, nospam wrote:
In article , PeterN
wrote:

I recently submitted two images to a competition. Bothe were 100 ppi and
measured, in pixels, 1020 x 768, both were saved at the same JPEG
compression level. Both files were saved as 8 bit JPEG.

there is no ppi in a jpeg file.

there is a tag that *suggests* an initial size, such as for a page
layout app (and that tag may not necessarily be used, depending on the
app), but other than that, the tag is meaningless.

ppi only matters when printing.

Yes. They intend to print certain images.

But the 72ppi they require fit no printer but that was the common ppi
of CRT screens.

This one is at least 100 ppi




anyone who requests a jpeg file at a specific ppi has no clue.

See above.


the pixel dimensions are what matters, and clearly they're stuck in the
1990s if they want it at 1024x768.

See rule 22.



--
PeterN