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Graphic Converter

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  Graphic Converter me@home.spamsucks.ca (Király) - 2016-04-23 16:51 +0000
    Re: Graphic Converter Jolly Roger <jollyroger@pobox.com> - 2016-04-23 19:53 +0000
    Re: Graphic Converter Nelson <nelson@nowhere.com> - 2016-04-23 17:44 -0400
      Re: Graphic Converter Jolly Roger <jollyroger@pobox.com> - 2016-04-24 03:21 +0000
        Re: Graphic Converter Nelson <nelson@nowhere.com> - 2016-04-24 06:50 -0400
          Re: Graphic Converter Jolly Roger <jollyroger@pobox.com> - 2016-04-24 15:31 +0000
          Re: Graphic Converter me@home.spamsucks.ca (Király) - 2016-04-25 03:52 +0000
            Re: Graphic Converter Jolly Roger <jollyroger@pobox.com> - 2016-04-25 16:32 +0000
              Re: Graphic Converter Nelson <nelson@nowhere.com> - 2016-04-26 07:26 -0400

#35361 — Graphic Converter

I have a PNG of an old map, it is all black with transparent background. 
Is there a way with Graphic Converter to select all of the black and 
change it all to white, while retaining the transparent background? I 
can't figure out how to do that without selecting each black element 
individually (there are hundreds) and changing them one at a time. 
Thanks.

-- 
K.

Lang may your lum reek.

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#35363

On 2016-04-23, Király <me@home.spamsucks.ca> wrote:
> I have a PNG of an old map, it is all black with transparent background. 
> Is there a way with Graphic Converter to select all of the black and 
> change it all to white, while retaining the transparent background? I 
> can't figure out how to do that without selecting each black element 
> individually (there are hundreds) and changing them one at a time. 

Have you tried Picture > Invert > Normal? You can accomplish what you
want with an inversion filter in apps like Pixelmator, Affinity Photo,
and so on as well.

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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#35373

On Sat, 23 Apr 2016 12:51:56 -0400, Király wrote
(in article <nfg97c$usn$1@dont-email.me>):

> I have a PNG of an old map, it is all black with transparent background. 
> Is there a way with Graphic Converter to select all of the black and 
> change it all to white, while retaining the transparent background? I 
> can't figure out how to do that without selecting each black element 
> individually (there are hundreds) and changing them one at a time. 
> Thanks.
> 
> 

Extract the alpha channel to a new window.  Select that window and 
change colors to 16 bit.  Invert.  Make black transparent.  Save as a 
new png.

-- 
Nelson

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#35380

Nelson <nelson@nowhere.com> wrote:
> On Sat, 23 Apr 2016 12:51:56 -0400, Király wrote
> 
> Extract the alpha channel to a new window.  Select that window and 
> change colors to 16 bit.  Invert.  Make black transparent.  Save as a 
> new png.

Picture > Invert > Normal seems way simpler. Try it out. It works great
here.

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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#35383

On Sat, 23 Apr 2016 23:21:16 -0400, Jolly Roger wrote
(in article <do2sdcFph4gU1@mid.individual.net>):

> Nelson <nelson@nowhere.com> wrote:
>> On Sat, 23 Apr 2016 12:51:56 -0400, Király wrote
>> 
>> Extract the alpha channel to a new window.  Select that window and 
>> change colors to 16 bit.  Invert.  Make black transparent.  Save as a 
>> new png.
> 
> Picture > Invert > Normal seems way simpler. Try it out. It works great
> here.

Yeah, that didn't work for me with the first example I tried.  I'm not 
sure why.  I may have had the white point set wrong or the color bit 
depth wrong or the transparency options wrong, or some other nonsense.  
Anyway,  I just tried again and it works as you say.

I'm not sure how transparency is implemented but it apparently requires 
an Alpha channel and the simple inversion didn't work for me in some 
cases.  Maybe it depends on the original color that was made 
transparent.  The sample I made to test was black text on transparent 
background to start with.

I don't have the time or interest to figure it out :)

-- 
Nelson

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#35385

Nelson <nelson@nowhere.com> wrote:
> On Sat, 23 Apr 2016 23:21:16 -0400, Jolly Roger wrote
> (in article <do2sdcFph4gU1@mid.individual.net>):
> 
>> Nelson <nelson@nowhere.com> wrote:
>>> On Sat, 23 Apr 2016 12:51:56 -0400, Király wrote
>>> 
>>> Extract the alpha channel to a new window.  Select that window and 
>>> change colors to 16 bit.  Invert.  Make black transparent.  Save as a 
>>> new png.
>> 
>> Picture > Invert > Normal seems way simpler. Try it out. It works great
>> here.
> 
> Yeah, that didn't work for me with the first example I tried.  I'm not 
> sure why.  I may have had the white point set wrong or the color bit 
> depth wrong or the transparency options wrong, or some other nonsense.  
> Anyway,  I just tried again and it works as you say.

Interesting...

> I'm not sure how transparency is implemented but it apparently requires 
> an Alpha channel and the simple inversion didn't work for me in some 
> cases.  Maybe it depends on the original color that was made 
> transparent.  The sample I made to test was black text on transparent 
> background to start with.
> 
> I don't have the time or interest to figure it out :)

Sounds like a plausible theory, anyway.

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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#35422

Nelson <nelson@nowhere.com> wrote:
> > Picture > Invert > Normal seems way simpler. Try it out. It works great
> > here.
> 
> Yeah, that didn't work for me with the first example I tried. 

At first I didn't think that it worked for me either, but then I 
zoomed in and yes all the black had turned to white. When zoomed out, 
for some reason GC adds a black outline to the white, making it look 
almost the same as the original all black image.

Thanks to both of you for the help.

-- 
K.

Lang may your lum reek.

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#35426

On 2016-04-25, Király <me@home.spamsucks.ca> wrote:
> Nelson <nelson@nowhere.com> wrote:
>> > Picture > Invert > Normal seems way simpler. Try it out. It works great
>> > here.
>> 
>> Yeah, that didn't work for me with the first example I tried. 
>
> At first I didn't think that it worked for me either, but then I 
> zoomed in and yes all the black had turned to white. When zoomed out, 
> for some reason GC adds a black outline to the white, making it look 
> almost the same as the original all black image.

That seems to be a silly design decision.

> Thanks to both of you for the help.

Glad you figured it out. : )

-- 
E-mail sent to this address may be devoured by my ravenous SPAM filter.
I often ignore posts from Google. Use a real news client instead.

JR

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#35469

On Mon, 25 Apr 2016 12:32:17 -0400, Jolly Roger wrote
(in article <do6v4hFqnouU1@mid.individual.net>):

> On 2016-04-25, Király <me@home.spamsucks.ca> wrote:
>> Nelson <nelson@nowhere.com> wrote:
>>>> Picture > Invert > Normal seems way simpler. Try it out. It works great
>>>> here.
>>> 
>>> Yeah, that didn't work for me with the first example I tried. 
>> 
>> At first I didn't think that it worked for me either, but then I 
>> zoomed in and yes all the black had turned to white. When zoomed out, 
>> for some reason GC adds a black outline to the white, making it look 
>> almost the same as the original all black image.
> 
> That seems to be a silly design decision.

Maybe not.  I suspect what he is seeing is the anti-aliasing at that 
magnification.

Lemke is a pretty smart cookie:)

-- 
Nelson

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