Re: image offset

On 2019-07-11 21:51, Bob Friesenhahn wrote:
> On Thu, 11 Jul 2019, mick crane wrote:
> 
>> I think what happens is $image -> crop
>> is some  memorized code that says take all these pixels from the x,y, 
>> width and height and save just those in a way identifiable as an image 
>> file.
>> But what is this offset thing ?
> 
> Sometimes it is useful to remember the offset that the cropped image
> came from.  It is sometimes an annoyance that PNG (and some other
> formats) remembers this and software may use it unexpectedly, but
> sometimes it is of great benefit.
> 
> There is a way to crop an entire image into a sequence of image tiles,
> and in this case is very useful for each tile to remember its original
> offset.
> 
> Bob

I think you might have misinterpreted what I meant by "stab in the dark 
syntax".
I am meaning *my* understanding of the Perl syntax.
Am I correct in thinking that there are not 2 libraries, methods, 
whatever they are called, but just the one
in the gm code.
so
"system (gm convert rose: -page "+22+48" crap.png);"

calls the same piece of code as
"$image->Convert(-page +22 +48);"
or something like that ?
and Graphics::Magick translates the syntax to call the gm code in a way 
it understands ?

I've mentioned I'm still struggling to understand how to use Perl but 
from what I have managed to comprehend find it really useful.
It is the proper method to send options in Perl to gm I could really do 
with help understanding.

cheers

mick



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