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Image size , A technical puzzle.



 
 
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  #21  
Old July 10th 15, 01:24 PM posted to rec.photo.digital,alt.photography
PeterN[_6_]
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Posts: 4,254
Default Image size , A technical puzzle.

On 7/10/2015 1:34 AM, Tony Cooper wrote:
On Thu, 9 Jul 2015 20:46:27 -0700, Savageduck
wrote:

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.


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.

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.

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.

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.

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.

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.

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.

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.

http://photography.nationalgeographi...contest/rules/


Of course there is no money involved. This is not a commercial
comeptition, just at a fun level. In a sense it is similar to our not
suspended "Shoot in."
I really wish someone would explain why two images with the same pixel
dimensions, and saved at the same compression level, would not be the
same size.

--
PeterN
  #22  
Old July 10th 15, 01:27 PM posted to rec.photo.digital,alt.photography
PeterN[_6_]
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Posts: 4,254
Default Image size , A technical puzzle.

On 7/10/2015 4:15 AM, nospam wrote:
In article , 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!


It does make a difference.


no it doesn't.

If I submit an image for a competition
that is more than 1400 pixels on the longest side, and/or not 72 ppi,
it will be rejected by the computer program that I use to upload the
image. It's happened to me.


what app is that?

regardless, a 72 ppi tag is meaningless.

what matters are the pixel dimensions, in your case 1400 or less.

I'm not defending the rule. I'm stating what it is. You aren't going
to drag me into an argument about why someone else came up with the
rule or whether they should have set that rule.

Your question, properly asked, is "Why did the competition committee
set that rule?". I have no answer for that. I don't set the rules.


the answer is because they're clueless dolts who don't understand what
they're doing.

My guess as to "why?" is that the competition committee wanted to
provide some parameters so people wouldn't ask "What ppi should I
use?".


that's a stupid reason.

such a question is an opportunity to teach the person asking what ppi
really means and why it makes no difference in an image that won't be
printed.


True, but some of these images will be printed.


unfortunately, a committee who has no clue is not in a position to do
that, as they don't understand it themselves.




--
PeterN
  #23  
Old July 10th 15, 01:33 PM posted to rec.photo.digital,alt.photography
nospam
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Posts: 24,165
Default Image size , A technical puzzle.

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.
  #24  
Old July 10th 15, 01:33 PM posted to rec.photo.digital,alt.photography
nospam
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Posts: 24,165
Default Image size , A technical puzzle.

In article , PeterN
wrote:

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.


Well, evidently you know what equipment all of the Camera Club
Councils in the US have. You must have learned that by a survey in
Coach. Or, since you've claimed that the people that run the group
are highly paid, you took the survey in First Class while peeping
through the curtain.

How do you come up with this wild hair of a theory, though? Dunno
about the NECCC, but the FCCC doesn't project the images at all in the
triannual competitions. The images are viewed online by the judges.
It says so in their webpage. You wouldn't be making **** up again,
would you?

If the NEFCCC is run the same as the FCCC (and I suspect it is), Peter
will not see his images projected. He will send them in and they will
view them online. The NEFCC is in Springfield MA, and Peter is in NY.
If he is among the 20/25% who win a ribbon, it will be sent to his
local camera club. His image will be up for view in on the NEFCC
webpage.


Actually, I submitted to a projected image competition, open only to
participants in the conference. I will have the opportunity to sit
through the judging, if I so desire.


in other words, tony is wrong (again) and talking out his ass (again).
  #25  
Old July 10th 15, 01:33 PM posted to rec.photo.digital,alt.photography
nospam
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Posts: 24,165
Default Image size , A technical puzzle.

In article , PeterN
wrote:

I really wish someone would explain why two images with the same pixel
dimensions, and saved at the same compression level, would not be the
same size.


as mentioned in other post, one has more detail than the other.
  #26  
Old July 10th 15, 01:33 PM posted to rec.photo.digital,alt.photography
nospam
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Posts: 24,165
Default Image size , A technical puzzle.

In article , PeterN
wrote:

My guess as to "why?" is that the competition committee wanted to
provide some parameters so people wouldn't ask "What ppi should I
use?".


that's a stupid reason.

such a question is an opportunity to teach the person asking what ppi
really means and why it makes no difference in an image that won't be
printed.


True, but some of these images will be printed.


it still doesn't matter, and at 1024x768, they won't be printed very
large (or they'll look like crap).
  #27  
Old July 10th 15, 01:33 PM posted to rec.photo.digital,alt.photography
PeterN[_6_]
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Posts: 4,254
Default Image size , A technical puzzle.

On 7/10/2015 4:31 AM, Eric Stevens wrote:
On Fri, 10 Jul 2015 04:15:31 -0400, nospam
wrote:

In article , 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!

It does make a difference.


no it doesn't.

If I submit an image for a competition
that is more than 1400 pixels on the longest side, and/or not 72 ppi,
it will be rejected by the computer program that I use to upload the
image. It's happened to me.


what app is that?

regardless, a 72 ppi tag is meaningless.

what matters are the pixel dimensions, in your case 1400 or less.

I'm not defending the rule. I'm stating what it is. You aren't going
to drag me into an argument about why someone else came up with the
rule or whether they should have set that rule.

Your question, properly asked, is "Why did the competition committee
set that rule?". I have no answer for that. I don't set the rules.


the answer is because they're clueless dolts who don't understand what
they're doing.


The answer is because they have always done it that way.


I must digress. I hired an accountant to do some work for a client. He
was driving. On the way home we were accompanied by a heavy snow storm.
The car heater was turned way up. When I asked him why, he said he liked
to drive with the sunroof open in cold weather. When we came to a light,
I opened the sunroof. He was not very happy, and didn't get my point.




--
PeterN
  #28  
Old July 10th 15, 01:40 PM posted to rec.photo.digital,alt.photography
PeterN[_6_]
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Posts: 4,254
Default Image size , A technical puzzle.

On 7/10/2015 2:59 AM, Tony Cooper wrote:
On Fri, 10 Jul 2015 02:01:00 -0400, nospam
wrote:

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


It's an area-wide umbrella organization that any camera club in the
New England area can join. Most states, or groups of states, have
one. It's not well-known outside of New England any more than the
FCCC is well-known outside of Florida.

There are CCCs all across the country.

I am absolutely amazed that you know the salaries of the people in an
organization clear across the country from you. You wouldn't be
making **** up again, would you?

http://www.neccc.org/p/clubs-join-neccc.html
http://www.neccc.org/p/about-us.html

limiting entries to 1024x768 and 1 megabyte is stupid.


NECCC entries are not limited to 1 megabyte. There's no requirement.
The rules say "It is suggested (though not a requirement) that entries
be saved with the proper amount of compression so that the file size
does not exceed 350 KB. If saving from Photoshop, a quality setting of
between 7 and 9 is usually sufficient to produce a high quality file.
Keeping the file size below 350 KB makes e-mailing and handling
easier."

Learn to read before you make a statement.

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??


Yep. We do it for the glory. Some of us are not afraid to show our
photos.

The $15 gift card beats what the NECCC and FCCC award: a cheap
ribbon. And, chances of winning a ribbon are pretty good. 20 to 25%
of the entries win a ribbon according to the websites.

It was more difficult to get recognition in the Shoot-In.

BTW...there is a cost to enter images at FCCC, but I don't know if
that's the case at NECCC. There is no cost to enter my club's
competition.


My CC does not charge a fee for entries. Our local umbrella organization
PFLI, Photographic Federation of Long Island, does not charge a fee either.

This NECCC competition is only open to participants in the anual
conferance. There is a late fee if the images are not entered by July 12.


--
PeterN
  #29  
Old July 10th 15, 02:13 PM posted to rec.photo.digital,alt.photography
Savageduck[_7_]
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Posts: 269
Default Image size , A technical puzzle.

On 2015-07-10 12:24:14 +0000, PeterN said:

I really wish someone would explain why two images with the same pixel
dimensions, and saved at the same compression level, would not be the
same size.


Actually two of us have given you an explaination. The file size of two
images cropped to identical pixel dimensions is going to be determined
by image data content which is a combination of detail area, contrast
level and color content.

For example, if those two identical dimensioned images were a sky scape
with large big color fields with little detail, and shot of a bird with
fine plumage detail, the file size for the bird might well be larger.

Given that, if you use the LR export method I have explained where the
dimensions are set and the file size limited after a crop to a specific
aspect ratio you will always be within the set export file size limit.

Here are two images cropped and sized to the same aspect ratio one is
11.9 MB the other 16.8 MB

On export, where I have set the file size limit at 1000 KB, the first
goes from 11.9 MB to 871 KB and the second goes from 16.8 MB to 836 KB.
The export dialog forced higher compresion on the larger original, but
both are now within the 1000 KB limit for the pixel dimensions I set.
They are both 2133 x 1200, or cropped to 16:9.
https://db.tt/614ommeD
https://db.tt/6buHT51P


--
Regards,

Savageduck

  #30  
Old July 10th 15, 02:57 PM posted to rec.photo.digital,alt.photography
Mayayana
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Posts: 1,514
Default Image size , A technical puzzle.

As others have said, details make the difference. JPG
compresses by dropping out data, which is why over
processing shows little rectangles. I just saved a 1020
x 768 JPG at compression level 8 and it's under 5 KB.
But it's just a solid blue field, so it's easy to store that
data as something that boils down to "783360 instances
of pixels of color 0, 0, 256". Interestingly, when I opened
the JPG in a hex editor it turns out that most of the
5 KB is just null byte filler. The "start of stream" marker
that indicates the beginning of the image data is two
bytes, FF DA. The actual image data seems to be only
17 or 18 bytes.


 




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