interpolation issues, HELP please

P
Posted By
Pavlov
Jun 25, 2005
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798
Replies
9
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Closed
Hi all,
PSP 7.01 here.
As you know, PSP shows clean images onlt with 100 % zoom or halves of this unit. I.E. a 66%, or a 54% zoomed image looks pretty bad. Now, since even XP’s Image preview handles interpolation in a good way, i wonder if there’s a way to show a CLEAN pic whatever zoom level i use.

Thanks,
Paolo
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T
Tacit
Jun 25, 2005
In article <m5cve.72006$>,
"Pavlov" wrote:

As you know, PSP shows clean images onlt with 100 % zoom or halves of this unit. I.E. a 66%, or a 54% zoomed image looks pretty bad. Now, since even XP’s Image preview handles interpolation in a good way, i wonder if there’s a way to show a CLEAN pic whatever zoom level i use.

Nope.

When you zoom out, Photoshop does a "nearest neighbor" interpolation for performance reasons. Photoshop is intended for professionals in the design and prepress community, who may routinely work with images that are 800 megabytes in size or larger. (I myself work with images in the 400MB-800MB range routinely, and have worked on images over a gigabyte in size.) If Photoshop were to use a different interpolation method to make zoomed-out images look cleaner, performance when zooming such large images would be unacceptable.

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
GH
Gernot Hoffmann
Jun 25, 2005
Tacit,

you are printing 1.5 x 1.5 m by 300 pixels per inch or
3.0 x 3.0 m by 150 pixels per inch ?

What’s the application ? Eye & nose on image ?

Best regards — Gernot Hoffmann

Mental calculation (I’m apologizing in advance if this
incredible calculation should be wrong):

900 MByte
300 Mpixels RGB
Squareroot
18000 pixels in one direction, roughly

300ppi: 60 inch width and height = 1.5m
150ppi: 120 inch width and height = 3.0m
MR
Mike Russell
Jun 25, 2005
"Pavlov" wrote in message
Hi all,
PSP 7.01 here.

Oops – this is Photoshop. But der Curvemeister is at your service anyway 🙂
\
As you know, PSP shows clean images onlt with 100 % zoom or halves of this unit. I.E. a 66%, or a 54% zoomed image looks pretty bad. Now, since even XP’s Image preview handles interpolation in a good way, i wonder if there’s
a way to show a CLEAN pic whatever zoom level i use.

PSP does not use XP’s image preview function, but it’s own native code for resizing. There may be an option to make this look better – I would check on a PaintShop Pro forum.

Photoshop displays a smoothly interpolated image at all zoom levels, and it works well due in part to Photoshop’s use of an internal "pyramid" structure that stores multiple resolution copies of the same image in memory – though there is an option to disable this if desired, for example on slower systems.
—

Mike Russell
www.curvemeister.com
P
Pavlov
Jun 26, 2005
Hi,

PSP does not use XP’s image preview function, but it’s own native code for resizing. There may be an option to make this look better – I would check on a PaintShop Pro forum.

I’m sorry… 😉 With that PSP i was meaning, well, Photoshop. I use Photoshop since 4.0, i’d never change it with anything else.

Photoshop displays a smoothly interpolated image at all zoom levels, and it works well due in part to Photoshop’s use of an internal "pyramid"
structure
that stores multiple resolution copies of the same image in memory –
though
there is an option to disable this if desired, for example on slower systems.

Mmm… Photoshop does *not* show a smoothly interpolated image at all zoom levels.
It does at 100, 50%, 25%, and so on. Try whatever else and you’ll get a really bad interpolation.
Unless i’m missing a basic option for years. Which option are you talking about ? Even with bicubic, Interpolation is wrong at odd zoom levels.

Not all people work on 400 mb pics, i mostly work on 50-100 MB ones; it’s time they put an option to get good interpolation at all zoom levels, machines are powerful now. I find very annoying havng to set zoom at even levels (100-50-25-12,5 etc) to work; i think with small pics we could get optimal performances even with a better interpolation.

Paolo
J
johnboy
Jun 26, 2005
"Pavlov" wrote:

I use Photoshop since 4.0, i’d never change it with anything else.
[…]

Not all people work on 400 mb pics, i mostly work on 50-100 MB ones; it’s time they put an option to get good interpolation at all zoom levels,
[…]

Makes no sense. You use 4.0 and won’t ever change but you think they should put in an option… and maybe they have, but you won’t ever change… so what?
MR
Mike Russell
Jun 26, 2005
"Pavlov" wrote in message

Unless i’m missing a basic option for years. Which option are you talking about ? Even with bicubic, Interpolation is wrong at odd zoom levels.

I was thinking of pixel doubling, but from what you’re saying this is not it.

Not all people work on 400 mb pics, i mostly work on 50-100 MB ones; it’s time they put an option to get good interpolation at all zoom levels, machines are powerful now. I find very annoying havng to set zoom at even levels (100-50-25-12,5 etc) to work; i think with small pics we could get optimal performances even with a better interpolation.

Now that you mention it, the preview zoom is less smooth than a bicubic to the same zoom level.

Good point. Windows has supported native bicubic interpolation for years – I believe since Win95 – so there is no reason not to do so in Photoshop. It’s particularly ironic because even with large pictures, most of the video boards out there provide hardware assisted scaling, so it would probably run faster than whatever code Photoshop is using.

I had been happy before, but now that you’ve pointed this out I’ll be seeing jaggies from now on. 🙂
—

Mike Russell
www.curvemeister.com
T
Tacit
Jun 26, 2005
In article ,
wrote:

you are printing 1.5 x 1.5 m by 300 pixels per inch or
3.0 x 3.0 m by 150 pixels per inch ?

You’re forgetting, images are often layered. 🙂

—
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
P
Pavlov
Jun 26, 2005
Makes no sense. You use 4.0 and won’t ever change but you think they
should
put in an option… and maybe they have, but you won’t ever change… so what?

Read again what i wrote: "I use Photoshop since 4.0". I guess that "since" makes the difference 😉
I’m using 7.01 now.

Paolo
GH
Gernot Hoffmann
Jun 26, 2005
Tacit,

IMO, the file size for a layered image in PSD can hardly be called the ‘size of an image’.

At least I’m knowing know what you are talking about.

Best regards –Gernot Hoffmann

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