Re: [Gimp-user] batches for web

2009-07-07 Thread David Gowers
On Wed, Jul 8, 2009 at 8:45 AM, Patrick Horgan wrote:
> The truth is that Gimp displays to you using your screen resolution, so if
> you originally created an image at 72dpi and 216x216 pixels and another
> image at 4800dpi and 216x216 pixels, Gimp will display them the same.
Sort of true, see below..

> While
> they look the same, if you look at image properties with  or
> set the disply units to inches in the bottom border and move around the
> image, you can see the difference.  One is reported as 3" across and the
> other as .045" across.  The resolution is used by Gimp to translate to
> inches and inch derived units for you.
>
> If you go into image/resize, and only change the dpi, Gimp will report to
> you that the image is a different size in inches, but the pixels are not in
> any way changed.
>
> Various image file types like jpg and png store resolution and Gimp does
> store that for you.  Devices are supposed to scale the images so that on
> their display resolution they will appear the same size as in the images
> native resolution.  Some devices/software actually do this.

Like GIMP (toggle View->Dot for Dot off). When Dot for Dot is off,
GIMP displays the image at a scale matching the comparitive
resolutions of the screen and the image.

>  If you print
> something and it comes out the wrong size, some times you can open it in
> Gimp, change the resolution and resave.  The only change will be in the
> stored resolution, the file's image data is completely unchanged, yet it
> will now print a different size!
___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user


Re: [Gimp-user] batches for web

2009-07-07 Thread Patrick Horgan




alec wrote:

  Hi...

  
  
Resolution (as in dots-per-inch) is irrelevant for images used on
web-pages. The only thing that counts is the number of pixels.


  
  Huh, I thought that lower resolution would make the file size smaller so
web images would load faster.  No?
  

Images on screens (which is how we view web images) are shown at 72-90
pixels/in.  72 used to be a pretty standard monitor resolution, but now
90pixels/in (or more) is common in this day of lcds.  Assuming 72
pixels/in  a 216x216 pixel image would look 3" across.  The same image
printed on a 300-2400dpi printer would be .72" (for 300dpi) to .09" 
(for 2400dpi).

When he said that resolution was irrelevant he meant that a 900 pixels
wide image doesn't really know it's resolution.  It's just 900 pixels
across which would take 12.5" to display on a 72dpi screen, 10" on a
90dpi screen, and only 3" to display on a 300dpi printer.  The truth is
that the image doesn't have a resolution, the display device does. 
(This is only mostly true as I'll explain in the last paragraph.)

The truth is that Gimp displays to you using your screen resolution, so
if you originally created an image at 72dpi and 216x216 pixels and
another image at 4800dpi and 216x216 pixels, Gimp will display them the
same.  While they look the same, if you look at image properties with
 or set the disply units to inches in the
bottom border and move around the image, you can see the difference. 
One is reported as 3" across and the other as .045" across.  The
resolution is used by Gimp to translate to inches and inch derived
units for you.

If you go into image/resize, and only change the dpi, Gimp will report
to you that the image is a different size in inches, but the pixels are
not in any way changed.  

Various image file types like jpg and png store resolution and Gimp
does store that for you.  Devices are supposed to scale the images so
that on their display resolution they will appear the same size as in
the images native resolution.  Some devices/software actually do
this.   If you print something and it comes out the wrong size, some
times you can open it in Gimp, change the resolution and resave.  The
only change will be in the stored resolution, the file's image data is
completely unchanged, yet it will now print a different size!

Patrick



___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user


Re: [Gimp-user] batches for web

2009-07-07 Thread Michael Schumacher
> Von: alec 

> > Resolution (as in dots-per-inch) is irrelevant for images used on
> > web-pages. The only thing that counts is the number of pixels.
> > 
> Huh, I thought that lower resolution would make the file size smaller so
> web images would load faster.  No?

Absolute resolution (aka 'image size'): yes

Relative resolution (aka 'pixels per inch'): no


See also "72 dpi myth", e.g. at http://www.scantips.com/no72dpi.html


HTH,
Michael
-- 
GRATIS für alle GMX-Mitglieder: Die maxdome Movie-FLAT!
Jetzt freischalten unter http://portal.gmx.net/de/go/maxdome01
___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user


Re: [Gimp-user] batches for web

2009-07-06 Thread Bob Long
alec wrote:

> Akkana Peck wrote:
[..]

>> Resolution (as in dots-per-inch) is irrelevant for images used on
>> web-pages. The only thing that counts is the number of pixels.
>>
> Huh, I thought that lower resolution would make the file size smaller so
> web images would load faster.  No?

Depends what you are *really* referring to.
See http://www.scantips.com/basics01.html

-- 
Bob Long
___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user


Re: [Gimp-user] batches for web

2009-07-06 Thread alec
Hi...

Akkana Peck wrote:
> Does Resize not do what you want? (I don't have DBP installed
> right now, but I thought it could scale images and looking
> at the web page I would guess Resize is what does that.)
Do you have a link to that plugin? I've searched quite a bit and David's
Batch processor has seemed the best so far, but I'm still(after a couple
years now) new to GIMP.
> 
>   ...Akkana
> 
Sven Neumann wrote:
> Hi,
> On Thu, 2009-07-02 at 15:43 -0400, alec wrote:
>> I finally installed David's Batch Processor (after months of trying to
>> figure out how to do batches) but I'm surprised that I don't see an
>> option for changing resolution.  I'm simply trying to prepare
>> images(lots of them) for the web.  Did I miss something in Daves
>> Batches?  Or maybe someone has a link to something else that would work
>> for me?  Thanks!
> 
> Resolution (as in dots-per-inch) is irrelevant for images used on
> web-pages. The only thing that counts is the number of pixels.
> 
Huh, I thought that lower resolution would make the file size smaller so
web images would load faster.  No?

Thanks-
Alec

>> ___
>> Gimp-user mailing list
>> Gimp-user@lists.XCF.Berkeley.EDU
>> https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user


Re: [Gimp-user] batches for web

2009-07-02 Thread Jay Smith


On 07/02/2009 04:06 PM, Sven Neumann wrote:
> Hi,
> 
> On Thu, 2009-07-02 at 15:43 -0400, alec wrote:
> 
>> I finally installed David's Batch Processor (after months of trying to
>> figure out how to do batches) but I'm surprised that I don't see an
>> option for changing resolution.  I'm simply trying to prepare
>> images(lots of them) for the web.  Did I miss something in Daves
>> Batches?  Or maybe someone has a link to something else that would work
>> for me?  Thanks!
> 
> Resolution (as in dots-per-inch) is irrelevant for images used on
> web-pages. The only thing that counts is the number of pixels.
> 
> 
> Sven

But... resolution is important for print output ... which is something I
am interested in.

So I think Alec's question still stands.

Jay
___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user


Re: [Gimp-user] batches for web

2009-07-02 Thread Sven Neumann
Hi,

On Thu, 2009-07-02 at 15:43 -0400, alec wrote:

> I finally installed David's Batch Processor (after months of trying to
> figure out how to do batches) but I'm surprised that I don't see an
> option for changing resolution.  I'm simply trying to prepare
> images(lots of them) for the web.  Did I miss something in Daves
> Batches?  Or maybe someone has a link to something else that would work
> for me?  Thanks!

Resolution (as in dots-per-inch) is irrelevant for images used on
web-pages. The only thing that counts is the number of pixels.


Sven


___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user


[Gimp-user] batches for web

2009-07-02 Thread alec
Howdy...
I finally installed David's Batch Processor (after months of trying to
figure out how to do batches) but I'm surprised that I don't see an
option for changing resolution.  I'm simply trying to prepare
images(lots of them) for the web.  Did I miss something in Daves
Batches?  Or maybe someone has a link to something else that would work
for me?  Thanks!
-Alec
___
Gimp-user mailing list
Gimp-user@lists.XCF.Berkeley.EDU
https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user