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 10/07/2015 2:32 p.m., 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.

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.


The more detail (colour, patterns etc) there is in an image, the larger
the file size at a standard compression "quality" setting.

On 2015-07-10 02:32:10 +0000, PeterN said:

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.

That seems like an odd aspect ratio and final print size, 10.2"x7.68"

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

Image content is going to play a part in the file size. How did they
differ in appearance?

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.

It is for a competition. It seems silly to reduce quality.

Why would there be such a large a difference?

See above: Image content.

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

If that is what you set the dimensions at and the EXIF for both is
identical other than the file size, the crop had nothing to do with it.

There is an easy way to ensure that all of your entries are within the
competition limits, without having to deal with any quality adjustments.

After you have made all of your adjustments, edits, and crops,
regardless of what you have used ( I am assuming that you are in PS
after having used DxO) Save your product as a TIFF or PSD. Import that
TIFF/PSD into Lightroom.
Then rather than the PS "Resize", "Save as", or "Export" options, use
the Lightroom "Export" dialog.

In that dialog you can create a preset with file size limits within the
competition requirements. There is no need to adjust the quality.
In this example I set the export destination to a folder labelled
"Competition" on my desktop. I limited the file size to 800KB, and that
will be regardless of the dimensions set. You can set the level of
metadata inclusion.

Then any other entries subject to the same competition rules just have
to be exported from Lightroom using the same export preset.
https://dl.dropboxusercontent.com/u/1295663/FileChute/screenshot_209.jpg

You might note that I have presets for export to Creative Cloud and
Dropbox folders.

--
Regards,

Savageduck

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.

Tony Cooper wrote:
I think you have to look at it from the viewpoint of the competition
committee. My own camera club requires a .jpg with the longest
dimension not to be more than 1400 pixels and at 72 ppi for the
monthly competitions. We do digital only now.

What difference would it make if the tag was set to 7
PPI? Or for that matter to 72000 PPI.

If it does make some difference, somebody is doing
something wrong!

In article , Tony Cooper
wrote:

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.


I think you have to look at it from the viewpoint of the competition
committee.

what for?

limiting entries to 1024x768 and 1 megabyte is stupid.

My own camera club requires a .jpg with the longest
dimension not to be more than 1400 pixels and at 72 ppi for the
monthly competitions. We do digital only now.

1400 pixels is better, but 72 ppi is meaningless unless it's printed,
which it won't be.

Each competition, will draw in 200 to 300 or more entries between the
three catagories (color, b&w, creative) with members allowed two
entries (not in the same catagory) each month.

in peter's case, the limit per entry is 1 megabyte, therefore 300
entries of two images would be at the most 600 megabytes, which would
fit on a single cd-rom.

typical hard drives today are 1 *terabyte*.

limiting the size of the entry is stupid.

The images are sent to the club and the club sends them as a file to
each of the three judges who review them and rate them from their home
or office on their own computers prior to the meeting night.

Whatever the opinion about the 72 ppi limit, all entries are treated
equally.

it's not a matter of opinion.

unless it's printed, there is no ppi. it's just pixels.

whatever the tag is set to makes no difference.

The bigger problem is that the judges may or may not have calibrated
monitors. An image may be seen differently by different judges, and
one may think it's, say, over-saturated and another may not see it
that way.

calibration is certainly an issue.

The judges are non-paid volunteers, so it's not really possible to
demand calibrated monitors. One of the three is an experienced club
member, and the other two are always outsiders with some connection or
experience in photography.

nonsense. of course it's possible.

a colour puck is cheap, but if they can't afford one, many members
would be happy to loan their own and possibly even calibrate it for the
club.

I don't know what Peter is entering, but most of us enter competitions
just to have our images critiqued by unbiased outsiders (the submitter
is anonymous) and to see our images displayed at the meeting. If
everyone's under the same rules, it's a level playing field.

based on his description, it's neccc, which is a rather well known
event with well paid staff.

There's no money involved, but the last time I won in a catagory I got
a $15 gift card from a camera store sponsor. Big whoop. The first
time I won I got a year's membership to SmugMug (donated by SmugMug),
but that's been a good investment for them because I've continued with
my membership, and paid for it, for several years now.

those were the prizes??

BTW...The National Geographic Photo Contest has a file size rule for
digital entries : 1600 pixels on the longest side and 20 megabytes or
smaller. I guess nospam thinks they are morons, and that's why he's
never entered.

that's a whole lot more than 1024x768 & 1 megabyte.

In article , Tony Cooper
wrote:

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.

There must be some national requirement involved in that 1024 number.
The Florida Camera Club Council has the following restrictions on
digital.

the reason is that they have old projectors which they've probably had
for years and refuse to upgrade. it's not like an hdtv projector is
that hard to find.

they are also too stupid to realize that computers and projectors can
scale to fit.

as i said initially, it's run by morons.

Sure enough, picking Texas I find that the GSCCC (Gulf States Camera
Club Council) requires 1024 x 768 pixels or smaller. No ppi stated.

that's slightly better. at least they realize ppi is meaningless.

Peter's not going to get anywhere educating the people who run the
NECCC. They're doing what all the CCCs do.

he might not, but that doesn't mean it's entirely a lost cause.