A current thread asks about monitor resolutions so that images could be
sent to fit most monitors. IMO, that is not a good idea. Your image file
should be the original, if at all possible. If you do think that
resizing it is desirable, reduce it, don't enlarge it. See below for the
reasons why. And reduce it as little as possible.

The display software can and will take care of resizing the image
display if that's what the end user wants. But that resizing of the
display will not change the image file itself.

IMO, the only reason for resizing an image is to reduce the file size,
to make transmission via the internet faster. But in doing this, you
will permanently lose image information, so it's a better idea to
compress the image, not resize it. Compressing cause some information
loss, but much less than resizing. (Cameras do a "lossless" compression,
which means that you can compress the image another 50% or so with no
noticeable loss of quality at the usual display or printing sizes.)

I think it might be a good idea to post two sizes of picture. 800x600
will give you a nice small files size, around 200K, so that the people
on dial-up can download it in a reasonable time. Files around 1200x800
or larger (files size 400K or more) are suitable for people on broadband.

Tech talk (you've been warned ;-))

There are two issues he the actual image size, and the displayed
image size. They are by no means the same thing, although they are
related. Both are measured in pixels, but that is all they have in common.

For example, if your monitor is at 1280 x 1024 pixels, then any image
smaller than this can be displayed as is. An actual 800x600 image will
display in the center of the display area with more or less white (or
black) space around it.

The smaller image could be expanded to fit the larger display area. The
display software does this by replacing blocks of pixels by larger
blocks of pixels. In doing this, it will distort some of the image
information, adding small detail where is none, for example. The effect
of this will be seen most obviously on diagonal lines, which will often
be turned into stair steps, called the jaggies. Better software will
smooth the jaggies, but there's a limit to what can be done.

OTOH, if the image is 1600x1200 pixels, the display software can reduce
the displayed image to 1280x1024. It does this by replacing groups of
pixels with smaller groups of pixels. This process loses some image
information, so that the displayed image will not have the same clarity
of small details, for example.

Most image viewers allow you to zoom in or out. This changes the
displayed image size.

In no case is the original image changed in any way.

When you resize the original image, the image processing software does
exactly what the display software does, but this time the changes are
permanent. The image file will be larger or smaller, depending on which
way you resized the image. In both cases, the image information will be
distorted. The smaller image will have less image information. Note that
you cannot recover this, it is permanently lost. The larger image will
have added false information. If you reduce an enlarged image, then some
of that false information will be retained (and you can't tell
beforehand what it will be.)

HTH

--


Wolf

"Don't believe everything you think." (Maxine)

Duh! You leave the original as is and save the reduced size for posting as
a separate file. The originals from my camera are 2560 x 1920 px, far
larger than will fit on any average user's monitor and the file sizes are as
large as 2 MB, no one wants to download a bunch of files that large. The
only time you need all that information is if you are making very large
prints.

Wolf wrote:
| A current thread asks about monitor resolutions so that images could
| be sent to fit most monitors. IMO, that is not a good idea. Your
| image file should be the original, if at all possible. If you do
| think that
| resizing it is desirable, reduce it, don't enlarge it. See below for
| the reasons why. And reduce it as little as possible.
|
| The display software can and will take care of resizing the image
| display if that's what the end user wants. But that resizing of the
| display will not change the image file itself.
|
| IMO, the only reason for resizing an image is to reduce the file size,
| to make transmission via the internet faster. But in doing this, you
| will permanently lose image information, so it's a better idea to
| compress the image, not resize it. Compressing cause some information
| loss, but much less than resizing. (Cameras do a "lossless"
| compression, which means that you can compress the image another 50%
| or so with no noticeable loss of quality at the usual display or
| printing sizes.)
|
| I think it might be a good idea to post two sizes of picture. 800x600
| will give you a nice small files size, around 200K, so that the people
| on dial-up can download it in a reasonable time. Files around 1200x800
| or larger (files size 400K or more) are suitable for people on
| broadband.
|
| Tech talk (you've been warned ;-))
|
| There are two issues he the actual image size, and the displayed
| image size. They are by no means the same thing, although they are
| related. Both are measured in pixels, but that is all they have in
| common.
|
| For example, if your monitor is at 1280 x 1024 pixels, then any image
| smaller than this can be displayed as is. An actual 800x600 image will
| display in the center of the display area with more or less white (or
| black) space around it.
|
| The smaller image could be expanded to fit the larger display area.
| The display software does this by replacing blocks of pixels by larger
| blocks of pixels. In doing this, it will distort some of the image
| information, adding small detail where is none, for example. The
| effect of this will be seen most obviously on diagonal lines, which
| will often be turned into stair steps, called the jaggies. Better
| software will smooth the jaggies, but there's a limit to what can be
| done.
|
| OTOH, if the image is 1600x1200 pixels, the display software can
| reduce the displayed image to 1280x1024. It does this by replacing
| groups of pixels with smaller groups of pixels. This process loses
| some image information, so that the displayed image will not have the
| same clarity of small details, for example.
|
| Most image viewers allow you to zoom in or out. This changes the
| displayed image size.
|
| In no case is the original image changed in any way.
|
| When you resize the original image, the image processing software does
| exactly what the display software does, but this time the changes are
| permanent. The image file will be larger or smaller, depending on
| which way you resized the image. In both cases, the image information
| will be distorted. The smaller image will have less image
| information. Note that you cannot recover this, it is permanently
| lost. The larger image will have added false information. If you
| reduce an enlarged image, then some of that false information will be
| retained (and you can't tell
| beforehand what it will be.)
|
| HTH

"Joan F (MI)" wrote in message
...
Duh! You leave the original as is and save the reduced size for posting
as
a separate file. The originals from my camera are 2560 x 1920 px, far
larger than will fit on any average user's monitor and the file sizes are
as
large as 2 MB, no one wants to download a bunch of files that large. The
only time you need all that information is if you are making very large
prints.

I tried to say something similar, but was accused of criticizing.
Somewhere along similar lines a question was raised about posting
(uploading) to these photo groups using a dpi of 300. Then the objection
was that monitors only display at a much lesser dpi. So all this
mumble-jumble only leads to more confusion. But I agree. I don't or
wouldn't post an original, unedited photo straight from the memory card. I
always save off the original to a dvd/cd for future use. Resize and edit
for posting. Dial-up, DSL, Cable. Doesn't matter. And how many of us
remember that we have downloaded tons of megabytes that are still sitting in
a file on your computer?

Wolf wrote:
A current thread asks about monitor resolutions so that images could
be sent to fit most monitors. IMO, that is not a good idea. Your
image file should be the original, if at all possible. If you do
think that resizing it is desirable, reduce it, don't enlarge it. See
below for
the reasons why. And reduce it as little as possible.

snip

Why on earth would anyone post the original size?...they are huge.
It's a simple matter to resize a photo for posting and save it as a copy and
retain the original for yourself.


I think it might be a good idea to post two sizes of picture. 800x600
will give you a nice small files size, around 200K, so that the people
on dial-up can download it in a reasonable time. Files around 1200x800
or larger (files size 400K or more) are suitable for people on
broadband.

snip

Which is a great time waster, ok for people with a lot of time, but not for
busy people. Then there's the hassle of sorting through the posts, checking
to see which ones to view and which to leave, more time wasting.

My personal opinion:
I cannot see why people want huge size files. A good photo is just that, the
composition, colour and clarity are much the same whether they be 1200x800
or 800x600.**
I'd be interested to hear just why people want to see large sized photos.
Speaking only for myself, I don't want to use an external viewer, such as
Irfanview, once again a time issue with me.

**tiny postage size thumbnail type photos excepted.

Joan F (MI) wrote:
Duh! You leave the original as is and save the reduced size for posting as
a separate file. The originals from my camera are 2560 x 1920 px, far
larger than will fit on any average user's monitor and the file sizes are as
large as 2 MB, no one wants to download a bunch of files that large.

Er, excuse me, but my name isn't "nobody." ;-)



[...]

3Putt from CoastalSouth Carolina wrote:
"Joan F (MI)" wrote in message
...
Duh! You leave the original as is and save the reduced size for posting
as
a separate file.

IMO, we should try for a consensus on file size, not image size. You can
set the image viewer (or newsreader) to reduce the displayed image to
fit your screen if you don;'tr want to scroll around to see the whole image.

The originals from my camera are 2560 x 1920 px, far
larger than will fit on any average user's monitor and the file sizes are
as
large as 2 MB, no one wants to download a bunch of files that large. The
only time you need all that information is if you are making very large
prints.

I tried to say something similar, but was accused of criticizing.
Somewhere along similar lines a question was raised about posting
(uploading) to these photo groups using a dpi of 300. Then the objection
was that monitors only display at a much lesser dpi. So all this
mumble-jumble only leads to more confusion. But I agree. I don't or
wouldn't post an original, unedited photo straight from the memory card.

Well, that's an esthetic choice, not a technical one. I prefer straight
photography, and don't like to edit photos. Not that I never edit
photos, but I usually do so to achieve a different effect, not to
produce the effect I was aiming for when I took the picture. A holdover
from my film days, I suppose. ;-)

BTW, have you noticed that if you apply certain filters to your image,
you actually increase the JPEG file size? That's because those filters
increase average differences between pixels, and compression relies on
the fact that in any one region of the image you are likely to have lots
of pixels low or even zero average differences.


I
always save off the original to a dvd/cd for future use. Resize and edit
for posting.

I suggest you edit before resizing. Resizing destroys some image
information, which reduces the effectiveness of the editing.


Dial-up, DSL, Cable. Doesn't matter. And how many of us
remember that we have downloaded tons of megabytes that are still sitting in
a file on your computer?


Fact is that most people have cameras that save images as lossless
JPEGs, not bitmaps, and definitely not in RAW format. A 4 megapixel
bitmap image is a great deal larger than 1 or 2 megabytes. (At 24 bits
per pixel, it's about 12MB. The RAW format image would be huge). The
lossless JPEG can be compressed another 50% or more - and many image
viewers will do this by default if you Save the image after displaying
it. (A poor design decision, IMO, but I guess the assumption is that if
you want to Save the image, you've tinkered with it.)

Keep in mind that the display software converts the JPEG to a bitmap,
saves that file in RAM, resizes it to fit the screen if set to do so,
and then sends the image to the video system. If you then Save the
displayed image, the software Saves the image in RAM to the HD,
compressing it first. The default compression is _not_ lossless, so that
the newly saved image is compressed more than the original -- smaller
file size. Actually, it's a quick and dirty way to reduce the image
you've copied from the memory card by about 50% to 70%, and I've often
done this.

BTW, it doesn't matter what dpi the original image is, what matters is
its resolution in pixels. Monitors display in pixels, not dpi. If you
have two monitors with the same resolution, the smaller one will have a
higher dpi than the larger one.

As for the scanner's dpi, that does matter. You will get the best
results if you scan at the scanner's _optical_ resolution, which is
always lower than the advertised "up to" resolution. Higher resolutions
are merely a digital zoom, and digital zoom does not increase the image
information. In fact, poor zoom algorithms will destroy information.

Bottom line: IMO we should try for a consensus on _file_ size. I suggest
200-400KB, or else both dial-up (say 150-300KB) and a broadband sizes
(say 500KB and up.)

HTH

--

Wolf

"Don't believe everything you think." (Maxine)

Marutchi wrote:
Wolf wrote:
A current thread asks about monitor resolutions so that images could
be sent to fit most monitors. IMO, that is not a good idea. Your
image file should be the original, if at all possible. If you do
think that resizing it is desirable, reduce it, don't enlarge it. See
below for
the reasons why. And reduce it as little as possible.

snip

Why on earth would anyone post the original size?...they are huge.
It's a simple matter to resize a photo for posting and save it as a copy and
retain the original for yourself.

Sigh. What's huge? As far as I am concerned, image doesn't matter here -
file size does. The 6MP camera I use saves the images as lossless JPEGs,
which are around 1.5 to 3MB in size (the more detail in the picture, the
less compression.) That's not huge, IMO. The original bitmap recorded
before conversion would be about 18MB. Now that I agree would be huge.

I think it might be a good idea to post two sizes of picture. 800x600
will give you a nice small files size, around 200K, so that the people
on dial-up can download it in a reasonable time. Files around 1200x800
or larger (files size 400K or more) are suitable for people on
broadband.

snip

Which is a great time waster, ok for people with a lot of time, but not for
busy people. Then there's the hassle of sorting through the posts, checking
to see which ones to view and which to leave, more time wasting.

I choose by subject header, and by sender - eg, I usually look at yours,
because you make very good photos, and besides the fauna you photograph
is something I likely will never see in person.


My personal opinion:
I cannot see why people want huge size files. A good photo is just that, the
composition, colour and clarity are much the same whether they be 1200x800
or 800x600.**

If there is a lot of subtle detail, then reducing down to 1200x800 or
800 x 600 will lose a lot of that subtle detail. That bothers me, for one.

I'd be interested to hear just why people want to see large sized photos.
Speaking only for myself, I don't want to use an external viewer, such as
Irfanview, once again a time issue with me.

Thunderbird does a fine job of rendering images, so it works well for
selecting which images to save (I save about 30% of the images I view,
and even that is probably too many.) But if I want to study a picture, I
use an external viewer. For one thing, I can get a full screen view that
way.


**tiny postage size thumbnail type photos excepted.




--


Wolf

"Don't believe everything you think." (Maxine)

"Joan F \(MI\)" expounded:

Duh! You leave the original as is and save the reduced size for posting as
a separate file. The originals from my camera are 2560 x 1920 px, far
larger than will fit on any average user's monitor and the file sizes are as
large as 2 MB, no one wants to download a bunch of files that large. The
only time you need all that information is if you are making very large
prints.

This is what I do. All of my pictures are saved in the original file
size and resized for posting.
--
Ann, gardening in Zone 6a
South of Boston, Massachusetts
e-mail address is not checked
******************************