Bicubic resample vs. smart resize

As an experiment, I compared the "bicubic resample" and the "smart resize" methods of reducing jpegs for sending vial email, using Paint Shop Pro 7, in each case keeping the size (5" wide) and resolution (72 ppi) the same. I sent the emails to myself, and, looking at the images in Microsoft Photo Editor, each of two photos treated in this manner was sharper in the bicubic resampled format. However, I also sent them to a friend, who says that when he looked at them with two different viewers (one was ACDSee; don't know about the other one), the smartsize version definitely looked better.

Any idea about what could be going on here?

Bob

Robert Deutsch said:

Any idea about what could be going on here?

Click to expand...

Yes, some providers and mail programs will actually RECOMPRESS jpg files that they get via mail to minimize their size. That really sucks because you can't control what your friend is getting. The best and only way around this HUGE problem is NOT send jpgs via email. Put them on a photo site and let your friend download them. Sending jpgs by mail is really hit and miss, I don't suggest you do it.

I suspect that the actual problem is that the bicubic file looks better but simply isn't compress as much as the smart resize, so it triggers a tougher compression when it arrives at your friends mail box. Major bummer because you never know what you will get in your mail.

If you HAVE to mail photos, zip them up. They will not be damaged in the mailing process that way, but it is more work for both your and your friend.

I had a similar problem yesterday, and I wasn't even testing anything. I edited a photo and sent it to a group of people, including myself at 2 different email addresses. I looked at the one I received at work, using Microsoft photo editor, and it looked horrible (kind of like the bad "variations" in Photoshop - all kinds of color splotches etc.). The one I sent to AOl and opened using Irfanview at home came out perfect, as did at least one I sent to a friend.

Very interesting. Another bit of relevant information is that my friend and I are at the same institution, with email addresses that use the same server. We both have high speed internet connections (I have DSL; he has cable). Could there still be differences in recompression? I use Outlook Express for email; I don't know what he uses. I could find out if you thought this could be a factor.

Bob

Serra said:

Robert Deutsch said:

Any idea about what could be going on here?

Click to expand...

Yes, some providers and mail programs will actually RECOMPRESS jpg
files that they get via mail to minimize their size. That really
sucks because you can't control what your friend is getting. The
best and only way around this HUGE problem is NOT send jpgs via
email. Put them on a photo site and let your friend download them.
Sending jpgs by mail is really hit and miss, I don't suggest you do
it.

I suspect that the actual problem is that the bicubic file looks
better but simply isn't compress as much as the smart resize, so it
triggers a tougher compression when it arrives at your friends mail
box. Major bummer because you never know what you will get in your
mail.

If you HAVE to mail photos, zip them up. They will not be damaged
in the mailing process that way, but it is more work for both your
and your friend.

Click to expand...

Hello

I did my own tests. I had one image with quite a lot of diagonal lines. I have resized it in all options on Paint Shop Pro. I like to send Pics in size 13x18cm, so that is, what I resized to (25% of original image).

It looks like Pixel Resize and Bicubic resize were the worst. Bilinear and smart size worked the best. I saved them with minimal compression as Jpegs.

Have a look here (never mind about the pic itself, it was just a test)

http://www.pbase.com/madpiano/test_pictures

Greetings
Sabine

Here are some help files regarding resampling from Paint Shop Pro 7 (bicubic resizing is meant for images that you want to expand):

"In the Resize Type box, select the type of resizing for Paint Shop Pro to apply. There are four choices:

· Smart size, where Paint Shop Pro chooses the best algorithm based on the current image characteristics.

· Bicubic resample, which uses a process called interpolation to minimize the raggedness normally associated with expanding an image. As applied here, interpolation smoothes out rough spots by estimating how the "missing" pixels should appear, and then filling them with the appropriate color. It produces better results than the Pixel resize method with photo-realistic images and with images that are irregular or complex. Use Bicubic resample when enlarging an image.

· Bilinear resample, which reduces the size of an image by applying a similar method as Bicubic resample. Use it when reducing photo-realistic images and images that are irregular or complex.

· Pixel Resize, where Paint Shop Pro duplicates or removes pixels as necessary to achieve the selected width and height of an image. It produces better results than the resampling methods when used with hard-edged images."

Isabel

Vixen of Verbiage

Serra said:

Robert Deutsch said:

Any idea about what could be going on here?

Click to expand...

Yes, some providers and mail programs will actually RECOMPRESS jpg
files that they get via mail to minimize their size. That really
sucks because you can't control what your friend is getting. The
best and only way around this HUGE problem is NOT send jpgs via
email. Put them on a photo site and let your friend download them.
Sending jpgs by mail is really hit and miss, I don't suggest you do
it.

I suspect that the actual problem is that the bicubic file looks
better but simply isn't compress as much as the smart resize, so it
triggers a tougher compression when it arrives at your friends mail
box. Major bummer because you never know what you will get in your
mail.

If you HAVE to mail photos, zip them up. They will not be damaged
in the mailing process that way, but it is more work for both your
and your friend.

Click to expand...

Robert,

I think that things are following:

1. There is no separate "smart resize" method. By choosing "smart resize" you are actually instructing PSP to choose resize method automaticaly.

2. Resize method in PSP can be bicubic (good for upsizing), bilinear (good for downsizing) or nearest neigbour (pixel resize.... need to check if it can be choosen from the resize dialog).

3. There are other interpolation methods, that PSP does not support. I have heard very positive opinions about Mitchell, B-Spline and Lanczos methods (for upsizing).

Take look at picture browser imageN (www.pixoid.com). It does support many resizing methods.

4. You can get much sharper picture if you resize in steps uzing bicubic method. Say, you want increase picture to a 200% of it's original size.

Try to resize it in steps, in each step resize it to 110% (or 105%) of original size until you will reach required size.--Cheers,Linas

Hi Linas, Robert,

In my opinion, the Lanczos algorithm works best, for both upsizing and downsizing. It is said to produce the sharpest thumbnails of all different filtering techniques. Nevertheless you could opt to sharpen final thumbnail images slightly.

In my tool ABC-View Manager you can see the difference between the crude windows resize method and sophisticated Lanczos III "on the fly". The image resize is first done "quick 'n' dirty" for responsive feedback, and then in the background the resampled image is calculated and displayed after some tenths of a second (or longer, for really large images).

You can also experiment with different settings for the filter. Under Options.. Viewer. (Box/Triangle/Hermite/Bell/Spline/Lanczos III/Mitchell)

Kind regards,
Nils Haeck
http://www.abc-view.com

Linas said:

Robert,

I think that things are following:

1. There is no separate "smart resize" method. By choosing "smart
resize" you are actually instructing PSP to choose resize method
automaticaly.

2. Resize method in PSP can be bicubic (good for upsizing),
bilinear (good for downsizing) or nearest neigbour (pixel
resize.... need to check if it can be choosen from the resize
dialog).

3. There are other interpolation methods, that PSP does not
support. I have heard very positive opinions about Mitchell,
B-Spline and Lanczos methods (for upsizing).

Take look at picture browser imageN (www.pixoid.com). It does
support many resizing methods.

4. You can get much sharper picture if you resize in steps uzing
bicubic method. Say, you want increase picture to a 200% of it's
original size.
Try to resize it in steps, in each step resize it to 110% (or 105%)
of original size until you will reach required size.
--
Cheers,
Linas

Click to expand...

Hey Nils,
I will definitelly take a look to ABC-View Manager !
--Cheers,Linas