L
Loony
Interesting observation Wolf. I'll stay with Mick's
http://bluefive.pair.com/pixresizer.htm.
Thanks Mick
http://bluefive.pair.com/pixresizer.htm.
Thanks Mick
W
Wolf K
Interesting observation Wolf. I'll stay with Mick's
http://bluefive.pair.com/pixresizer.htm.
Thanks Mick
You can resize the image in Irfanview: Image > Resize/Resample, or
Control+R.
You can also change "canvas Size", Shift+V, it's a quick way to add a
black border, but can be used for other effects, too.
HTH
Wolf K.
M
mick
I have found that to just resize images Pixresizer gives a much smallerInteresting observation Wolf. I'll stay with Mick's
http://bluefive.pair.com/pixresizer.htm.
Thanks Mick
You can resize the image in Irfanview: Image > Resize/Resample, or Control+R.
You can also change "canvas Size", Shift+V, it's a quick way to add a black
border, but can be used for other effects, too.
HTH
Wolf K.
file size than any other software I have and that includes Irfanview,
Faststone, ACDSee Pro 4, Photoshop Elements 9 and PhotoPlus X5.
I have just run a test resizing an original .jpg image of 2816x1880x24,
file size 3782kb on all the above software, resizing the file as
1200x801x24, to 90% quality in all software.
The following reduced file sizes produced were:
Irfanview 970kb
Faststone 950kb
ACDSee Pro 4 1120kb
Photoshop Elements 9 1140kb
Photoplus X5 942kb
Pixresizer 374kb
Quite a difference for Pixresizer, I cannot see any difference between
any of the resized images as regards to quality or loss of definition.
J
J. P. Gilliver (John)
There are (at least) three things "resize" and similar terms can mean
when discussing an image:
o changing the size of the file on disc
o changing the number of pixels *at 1:1 zoom*
o changing how big the image is displayed on screen.
The last doesn't affect the other two; the first _may_ not affect the
second.
I think this thread has been rather confusing, because I suspect various
posters have been talking about different things, and not realising this
fact. (Any one poster has _probably_ been consistent in his own posts.)
JPGs; this has an effect on the filesize produced. (So you need to say
what that was set to in any such comparison table. I _think_ it defaults
to "80%", but I also think it's "sticky", i. e. if you change it it
stays changed.)
when discussing an image:
o changing the size of the file on disc
o changing the number of pixels *at 1:1 zoom*
o changing how big the image is displayed on screen.
The last doesn't affect the other two; the first _may_ not affect the
second.
I think this thread has been rather confusing, because I suspect various
posters have been talking about different things, and not realising this
fact. (Any one poster has _probably_ been consistent in his own posts.)
Thanks, sounds like one worth remembering!mick said:
IV - I don't know about the others - has a quality slider for saving
JPGs; this has an effect on the filesize produced. (So you need to say
what that was set to in any such comparison table. I _think_ it defaults
to "80%", but I also think it's "sticky", i. e. if you change it it
stays changed.)
M
mick
There are (at least) three things "resize" and similar terms can mean when
this has an effect on the filesize produced. (So you need to say what that
was set to in any such comparison table. I _think_ it defaults to "80%", but
I also think it's "sticky", i. e. if you change it it stays changed.)
What I tested was reducing the same image from 2816x1880 pixels to
1200x801 pixels in all cases to 90% quality. Pixresizer defaults to
90%, the other softwares have different default settings but these were
also set to 90% for the test. Yes, they are all "sticky" and stay
changed.
Thanks, sounds like one worth remembering!
IV - I don't know about the others - has a quality slider for saving JPGs;
this has an effect on the filesize produced. (So you need to say what that
was set to in any such comparison table. I _think_ it defaults to "80%", but
I also think it's "sticky", i. e. if you change it it stays changed.)
[/QUOTE]
What I tested was reducing the same image from 2816x1880 pixels to
1200x801 pixels in all cases to 90% quality. Pixresizer defaults to
90%, the other softwares have different default settings but these were
also set to 90% for the test. Yes, they are all "sticky" and stay
changed.
W
Wolf K
Very small files are not necessarily a good thing. I certainly wouldn't
do this for archiving pictures, and would hesitate to do it even for
e-mailing. (My bro' has a Mac, which automatically "adjusts" images for
e-mailing. The result is very small pictures that show the jaggies
beginning at 150% zoom! I'd much rather he e-mailed the original files).
Keep in mind that resizing an image in pixel dimensions _always_ results
in data loss. I would be suspicious of a resizing algorithm that
produces significantly smaller image files: the odds are that there is
greater data loss. Whether you will perceive that data loss as a
degraded image depends on a number of factors, including your own eyes.
Our visual system automatically adjusts the image actually projected
onto our retinas so that we "see" a pretty good version of whatever
we're looking at. It's an illusion, of course, but I can live with that.
;-) Personally, I prefer higher quality over smaller file size.
Background facts:
When you reduce image size by reducing its pixel dimensions, then a
cluster of pixels is replaced by a single pixel. If you halve the
dimensions (say from 4000 x 3000 to 2000 x 1500), then 1 pixel replaces
4. You can see that this is not a simple process: some kind of averaging
of neighbouring pixels must be done. Programs differ in how they do it.
But whichever way it's done, 1 pixel cannot store 4 pixels worth of
image data.
The other way to reduce file size is compression. Compression may or may
not result in data loss, depending on the compression scheme. Basically,
compression replaces a string of identical pixels with a few bytes that
specify the number of pixels and their colour. Thus, a compressed image
file can preserve all the image data of the original image. An image
with large areas of the same colour will be compressed more than one
with large amounts of fine detail.
The most widely used compression method is JPEG. JPEG can be set to "low
quality", in which "nearly the same" pixels are treated as if they were
the same. This results in a much smaller file size, but at the cost of
data loss. At high quality (about 90%), the JPEG image will be about 25%
the size of the raw image. At this quality, the human eye cannot
perceive the loss in data. You would perhaps see the difference if you
printed the image as a poster, but that also depends on how the printer
driver deals with the image (which is a whole 'nother issue).
In Irfanview you can set the quality of the JPEG file: lower quality -->
smaller file size. I've set all my image viewers to 90%, which means
that any processed image results in a file size about the same as the
original. That way, the processed image contains about the same amount
of image data as the original.
HTH
Wolf K.
M
mick
All good points Wolf. It is a balancing act at the end of the day as
to why you need to resize the image. I don't know what other people
do, but I NEVER destroy the original image. All images that I resize
are done for posting to binary groups, email or sometimes to web sites,
where it is the visual on-screen effect that is more important. If
anyone requires a copy of the original to work on, or print, then it is
available although the method of sending/downloading may not be as easy
for non-tech savvy people.