When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Rudolf Bahr]

Hi All,

from an external figure I normally know its width and height in px. 
But I don't know its exact sizes in pt. When newsizing the figure 
in a document (by the same width-to-height-ratio), I'll do that as 
some part of textwidth or textheight, in pt or mm, but not in px, 
i.e. by means of [width=<some pt>]. 
Sometimes it would be interesting to know its new height in pt, 
and viceversa. 

Is there a variable or something else containing its new size in pt?

Regards,
Rudolf

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Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Rudolf Bahr]

On Tue, Feb 19, 2019 at 10:48:38AM +0100, Bahr Rudolf wrote:
> Hi All,
> 
> from an external figure I normally know its width and height in px. 
> But I don't know its exact sizes in pt. When newsizing the figure 
> in a document (by the same width-to-height-ratio), I'll do that as 
> some part of textwidth or textheight, in pt or mm, but not in px, 
> i.e. by means of [width=<some pt>]. 
> Sometimes it would be interesting to know its new height in pt, 
> and viceversa. 
> 
> Is there a variable or something else containing its new size in pt?
> 
> Regards,
> Rudolf




Hi All,

up to now Nobody answered to my question, perhaps it might have been
too simple.

Indeed One could normally assume:


picture-width-in-px      preset-picture-width-in-pt
--------------------  =  --------------------------
picture-height-in-px     asked-picture-height-in-pt


And according to Adam Riese One gets:

                             preset-picture-width-in-pt  *  picture-height-in-px
asked-picture-height-in-pt = ---------------------------------------------------
                                             picture-width-in-px


-----------------
The picture sizes in px One gets by invoking for instance graphics Magick's identify
in a lua program:

local file = assert ( io.popen ( 'gm identify ' .. picture_name, 'r' ))
local output = file:read ( '*all' )
file:close ()

local words = {}
for w in string.gmatch ( output, "%g+" ) do
    words [ #words + 1 ] = w
end

-- Width and height are found in words[3]: i.e. 5407x3544+0+0
local dims = {}
for d in string.gmatch ( words [ 3 ], "%d+" ) do
    dims [ #dims + 1 ] = d
end

local px_width  = dims [ 1 ]
local px_height = dims [ 2 ]
-----------------

It's a solution at least as long as your Lua supports "io.popen". There might be
shorter solutions.

Cheers, Rudolf

 
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Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Peter Münster]

On Fri, Feb 22 2019, Rudolf Bahr wrote:

> The picture sizes in px One gets by invoking for instance graphics Magick's identify
> in a lua program:

Or just img.scan():

\startluacode
  local image = img.scan{filename = "my-image.jpg"}
  logs.report("xsize", image.xsize)
  logs.report("ysize", image.ysize)
\stopluacode

-- 
           Peter
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Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Rudolf Bahr]

On Fri, Feb 22, 2019 at 12:59:55PM +0100, Peter Münster wrote:
> On Fri, Feb 22 2019, Rudolf Bahr wrote:
> 
> > The picture sizes in px One gets by invoking for instance graphics Magick's identify
> > in a lua program:
> 
> Or just img.scan():
> 
> \startluacode
>   local image = img.scan{filename = "my-image.jpg"}
>   logs.report("xsize", image.xsize)
>   logs.report("ysize", image.ysize)
> \stopluacode
> 
> -- 
>            Peter

Hi Peter,

thank you for pointing to img.scan{}! It's indeed shorter than to invoke Graphics Magick
in Lua. Remains the conversion of image sizes into pt. There is an example in the chapter
"Calculations in Lua" in "https://wiki.contextgarden.net/Image_Placement" (a work in
progress). According to there it's necessary to know the resolution in order to convert
image sizes from px to pt which at least I don't know. Mostly I can preset one size of
a picture (say the width in pt) to be able to place it on a page and assuming
x-resolution = y-resolution and keeping width-to-height ratio I calculate the missing
size (here the height in pt) in Lua by

                                                            picture-height-in-px
asked-picture-height-in-pt = preset-picture-width-in-pt  *  --------------------
                                             		    picture-width-in-px

This is simple and normally it suffices for me.

Rudolf

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Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Hans Hagen]

On 2/23/2019 11:08 AM, Rudolf Bahr wrote:
> On Fri, Feb 22, 2019 at 12:59:55PM +0100, Peter Münster wrote:
>> On Fri, Feb 22 2019, Rudolf Bahr wrote:
>>
>>> The picture sizes in px One gets by invoking for instance graphics Magick's identify
>>> in a lua program:
>>
>> Or just img.scan():
>>
>> \startluacode
>>    local image = img.scan{filename = "my-image.jpg"}
>>    logs.report("xsize", image.xsize)
>>    logs.report("ysize", image.ysize)
>> \stopluacode
>>
>> -- 
>>             Peter
> 
> Hi Peter,
> 
> thank you for pointing to img.scan{}! It's indeed shorter than to invoke Graphics Magick
> in Lua. Remains the conversion of image sizes into pt. There is an example in the chapter
> "Calculations in Lua" in "https://wiki.contextgarden.net/Image_Placement" (a work in
> progress). According to there it's necessary to know the resolution in order to convert
> image sizes from px to pt which at least I don't know. Mostly I can preset one size of
> a picture (say the width in pt) to be able to place it on a page and assuming
> x-resolution = y-resolution and keeping width-to-height ratio I calculate the missing
> size (here the height in pt) in Lua by
> 
>                                                              picture-height-in-px
> asked-picture-height-in-pt = preset-picture-width-in-pt  *  --------------------
>                                               		    picture-width-in-px
> 
> This is simple and normally it suffices for me.
Better use the built-in methods:

\starttext

     \getfiguredimensions[t:/sources/mill.png]

     (\figurewidth,\figureheight)

     (\figurexsize,\figureysize)

\stoptext

as it prevents opening the files multiple times. It's also more futureproof.

Hans

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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Rudolf Bahr]

On Sat, Feb 23, 2019 at 11:56:32AM +0100, Hans Hagen wrote:
> On 2/23/2019 11:08 AM, Rudolf Bahr wrote:
> > On Fri, Feb 22, 2019 at 12:59:55PM +0100, Peter Münster wrote:
> > > On Fri, Feb 22 2019, Rudolf Bahr wrote:
> > > 
> > > > The picture sizes in px One gets by invoking for instance graphics Magick's identify
> > > > in a lua program:
> > > 
> > > Or just img.scan():
> > > 
> > > \startluacode
> > >    local image = img.scan{filename = "my-image.jpg"}
> > >    logs.report("xsize", image.xsize)
> > >    logs.report("ysize", image.ysize)
> > > \stopluacode
> > > 
> > > -- 
> > >             Peter
> > 
> > Hi Peter,
> > 
> > thank you for pointing to img.scan{}! It's indeed shorter than to invoke Graphics Magick
> > in Lua. Remains the conversion of image sizes into pt. There is an example in the chapter
> > "Calculations in Lua" in "https://wiki.contextgarden.net/Image_Placement" (a work in
> > progress). According to there it's necessary to know the resolution in order to convert
> > image sizes from px to pt which at least I don't know. Mostly I can preset one size of
> > a picture (say the width in pt) to be able to place it on a page and assuming
> > x-resolution = y-resolution and keeping width-to-height ratio I calculate the missing
> > size (here the height in pt) in Lua by
> > 
> >                                                              picture-height-in-px
> > asked-picture-height-in-pt = preset-picture-width-in-pt  *  --------------------
> >                                               		    picture-width-in-px
> > 
> > This is simple and normally it suffices for me.
> Better use the built-in methods:
> 
> \starttext
> 
>     \getfiguredimensions[t:/sources/mill.png]
> 
>     (\figurewidth,\figureheight)
> 
>     (\figurexsize,\figureysize)
> 
> \stoptext
> 
> as it prevents opening the files multiple times. It's also more futureproof.
> 
> Hans
> 

Hi Hans,

I fear it doesn't work. I used the above code with a test-picture of mine
(in .png and .jpg version) and got:

(0sp,0sp)
(0,0)

Now I'm baffled what the explanation could be. Are "mill" or "cow" somehow
specially prepared? I used:

ConTeXt  ver: 2018.03.16 22:20 MKIV beta  fmt: 2018.3.21 and
getfiguredimensions[~/my-test-picture.png]

Rudolf
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Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Hans Hagen]

On 2/23/2019 12:37 PM, Rudolf Bahr wrote:
> On Sat, Feb 23, 2019 at 11:56:32AM +0100, Hans Hagen wrote:
>> On 2/23/2019 11:08 AM, Rudolf Bahr wrote:
>>> On Fri, Feb 22, 2019 at 12:59:55PM +0100, Peter Münster wrote:
>>>> On Fri, Feb 22 2019, Rudolf Bahr wrote:
>>>>
>>>>> The picture sizes in px One gets by invoking for instance graphics Magick's identify
>>>>> in a lua program:
>>>>
>>>> Or just img.scan():
>>>>
>>>> \startluacode
>>>>     local image = img.scan{filename = "my-image.jpg"}
>>>>     logs.report("xsize", image.xsize)
>>>>     logs.report("ysize", image.ysize)
>>>> \stopluacode
>>>>
>>>> -- 
>>>>              Peter
>>>
>>> Hi Peter,
>>>
>>> thank you for pointing to img.scan{}! It's indeed shorter than to invoke Graphics Magick
>>> in Lua. Remains the conversion of image sizes into pt. There is an example in the chapter
>>> "Calculations in Lua" in "https://wiki.contextgarden.net/Image_Placement" (a work in
>>> progress). According to there it's necessary to know the resolution in order to convert
>>> image sizes from px to pt which at least I don't know. Mostly I can preset one size of
>>> a picture (say the width in pt) to be able to place it on a page and assuming
>>> x-resolution = y-resolution and keeping width-to-height ratio I calculate the missing
>>> size (here the height in pt) in Lua by
>>>
>>>                                                               picture-height-in-px
>>> asked-picture-height-in-pt = preset-picture-width-in-pt  *  --------------------
>>>                                                		    picture-width-in-px
>>>
>>> This is simple and normally it suffices for me.
>> Better use the built-in methods:
>>
>> \starttext
>>
>>      \getfiguredimensions[t:/sources/mill.png]
>>
>>      (\figurewidth,\figureheight)
>>
>>      (\figurexsize,\figureysize)
>>
>> \stoptext
>>
>> as it prevents opening the files multiple times. It's also more futureproof.
>>
>> Hans
>>
> 
> Hi Hans,
> 
> I fear it doesn't work. I used the above code with a test-picture of mine
> (in .png and .jpg version) and got:
> 
> (0sp,0sp)
> (0,0)
> 
> Now I'm baffled what the explanation could be. Are "mill" or "cow" somehow
> specially prepared? I used:
> 
> ConTeXt  ver: 2018.03.16 22:20 MKIV beta  fmt: 2018.3.21 and
> getfiguredimensions[~/my-test-picture.png]

maybe the image is not found ... what if you replace the ~



-- 

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------
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Re: When newsizing an external figure bei [width=<some pt>], what will be its height in pt and viceversa?

[Jeong Dal]

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Dear Rudolf,

It is working for me.
Using my figure, I got 
(45126287sp,31048991sp) 

(1372,944) 


As Hans said, either change ~ to some path or set the directory of externalfigure.

Best regards,

Dalyoung

> 2019. 2. 24. 오전 5:58, ntg-context-request@ntg.nl 작성:
> 
> I fear it doesn't work. I used the above code with a test-picture of mine
> (in .png and .jpg version) and got:
> 
> (0sp,0sp)
> (0,0)
> 
> Now I'm baffled what the explanation could be. Are "mill" or "cow" somehow
> specially prepared? I used:
> 
> ConTeXt  ver: 2018.03.16 22:20 MKIV beta  fmt: 2018.3.21 and
> getfiguredimensions[~/my-test-picture.png]
> 
> Rudolf


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