[Gimp-user] problems with understand how to resize images properly

[menglor <forums gimpusers com>]

Thanks for your reply.  I am reading through what your saying, and I cross
posted this question on another site and getting a similar answer.

I dont want to duplicate the work, but I need to get some kind of "simple"
working solution. so I am hoping I can comment a few things and maybe drive the
conversion differently and maybe something I missed will come out.

I understand GIMP and probably ALL graphical software behaves similarly. and I
dont expect that will change. but here is my dilema.

I have a working surface of  2.42 x 1.30  to display what I am trying to do. the
specification are that. and I can be smaller  on the 2.42,  but I have to be
Razor sharp on the 1.3 measurements when I print the label.

Its been mu experience, with Gimp, I can get the 1.3 nailed on the screen, and I
have to fill in from 2.0 to 2.4 with a color match because scaling isnt bang on.

As well, what I am capturing from multiple sources so DPI and physical size will
change.  and I would rather it take minutes rather then hours to do it.

The part I am struggling with is your comment: 

Example:  A 300 DPI image scaled to 1" x 1" will come out 300 pixels wide.  A
150 DPI image scaled to 1" x 1" will come out 150 pixels wide  half "size" of
the 300 DPI one.

its somewhat ODD for me to hear,  that a 1 x 1 inch image, is half the size of
another 1 x 1 inch image.

If I was building an engine for your car, and you told me it has to  24" by 48"
and I delivered you an engine that was double that, you would laugh at me, and
it wouldnt fit.

and I will go one further and even replicate a comment I posted elsewhere,   
When I created a 1" x 1" image at 300 dpi,  Gimp still showed me the image on
the screen with a ruler as 1" x 1", but when I pasted the object into MS Paint, 
it said it was 3"

So, with all that whining done, let me ask this question.

- I need to create an image that is 2.42 x 1.30 in size.  
- I know when I scale any image to 1.3 I end up with a 2.0 x 1.3 image.
- I need to be able to take ANY image I want.  scale it down to size
- Fill in the buffer between  2.42 and 2.0 with the appropriate background
color.
- Paste it into "something" that will allow me to print it too a Avery label
sheet.
- Cut it with a knife and apply it on a surface like a tube, where the
circumference of the item is 1.3" in size.
- There can be no over lap.

- its been suggested, that I resize the image in Word or other programs outside
of Gimp, but Word or other programs
dont offer the granularity or precision that Gimp does,  so from my view point,
its like asking me to write my resume in Excel.

Do you have any suggestions ?   I will be looking at Scribus tonight or Friday.
But I am looking for a solution to render the above in a fairly short period of
time, the Avery templates have 10 labels. and I never expect to print the same
picture twice.





> Hi menglor,
>
> The process you describe will give you images of different sizes if
> the
> originals have different DPI values, because when you scale an image
> to
> be a certain number of inches in size, the GIMP looks at the DPI
> resolution of the image first, then scales the image to be X number of
> pixels wide/tall based on that DPI and the physical dimensions you
> specify.
>
> Example:  A 300 DPI image scaled to 1" x 1" will come out 300 pixels
> wide.  A 150 DPI image scaled to 1" x 1" will come out 150 pixels wide
> -
> half "size" of the 300 DPI one.
>
> Scaling images by adjusting their size in inches (or centimeters,
> etc.)
> is rarely done.  Useful results require resetting the DPI of images as
> necessary, so a set of images of the same size in inches, cm or etc.
> will also be the same size in pixels.
>
> Or can multiply the size in inches of the output images you want by
> the
> DPI you want, to get the correct dimensions in pixels for /all/ the
> images intended to be the same size when printed.  From that point on,
> you can just scale your whole batch of images to the same size in
> pixels
> and ignore the size "in inches."
>
> The DPI setting in an image is only a number recorded in the file
> header; changing the DPI of an image changes nothing but that one
> number, and as far as I know it does not affect the actual or
> displayed
> / printed size of the image, except when scaling the image in an
> editor
> like the GIMP.
>
> Typical DPI values:
>
> 300 DPI for high quality print
> 150 DPI for office documents etc. where "good enough is good enough"
> 96 DPI for on-screen display
> 72 DPI - a legacy default setting based on printers' "point" size
>
> Note that doubling the DPI of an image while maintaining the same
> print
> size when scaling, multiplies the size of the resulting file on disk
> by
> about 4x.  Exporting images in lossless PNG format (vs. lossy JPG) for
> maximum print quality also creates much larger file sizes on disk.  So
> big, high quality print jobs can take up a lot of space in storage or
> time in transit across the network.
>
> You also mentioned printing via a Word document, and that the sizes
> you
> get are a little off.  I think that's to be expected, because word
> processors were not intended for "pre-press" work, a.k.a. printing
> images with high accuracy.
>
> I use Scribus, a Free desktop publishing application, for pre-press
> work.  Make your images, put them on the page exactly where you want
> them, export the file as PDF and print that:  Viola, accurate results.
>
> For really precise positioning on page, i.e. when printing on peel and
> stick label stock or etc., it may be necessary to print a test page,
> measure any placement errors, and adjust the Scribus master document
> to
> get your required results from that particular printer.
>
> https://www.scribus.net/
>
> :o)

-- 
menglor (via www.gimpusers.com/forums)