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 Post subject: Trace Bitmap
PostPosted: Fri Oct 31, 2014 11:15 am  (#1) 
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I have just been reading regarding the Trace Bitmap utility in Inscape.

I have a beginers question.

If someone uploads a Bitmap into Inscape, why not just use it, rather than use Trace? As you can see,I am missing something.

What is the advantage of using Trace?

Thanks

Ps. I have asked at this point because it make it easier for me to learn.

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 Post subject: Re: Trace Bitmap
PostPosted: Fri Oct 31, 2014 11:48 am  (#2) 
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Bitmap image is a raster image, i.e. a bunch of pixels, with
pre-defined resolution (just zoom in to see ever increasing pixelation).
Vector is a mathematical expression, unlike raster, it is a resolution
independent image. Theoretically, you can zoom-in vector elements
infinitely* without pixelation.

In practical terms, e.g. scaling up raster image
to 1000% will most certainly destroy it, for vector images it won't even matter.

*there is a limit after all, but only software wise: IIRC, Inkscape 12500%, Illustrator 6400%,
Affinity Designer - 1 000 000 %.

Hope this helps.


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 Post subject: Re: Trace Bitmap
PostPosted: Fri Oct 31, 2014 12:12 pm  (#3) 
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anon_private wrote:
I have just been reading regarding the Trace Bitmap utility in Inscape.

I have a beginers question.

If someone uploads a Bitmap into Inscape, why not just use it, rather than use Trace? As you can see,I am missing something.

What is the advantage of using Trace?

Thanks

Ps. I have asked at this point because it make it easier for me to learn.


You have to understand the difference between raster/bitmap graphics and vector graphics, which is fairly well explained on Wikipedia. You can also envision bitmap as painting a brick wall using a color per brick, while vector graphics are instructions to move the paintbrush over the wall.

Of course, when the image is really complex (photography) a bitmap is better, but most simple images (logo, text, cartoons...) are better described as vectors.

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 Post subject: Re: Trace Bitmap
PostPosted: Fri Oct 31, 2014 12:24 pm  (#4) 
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I do understand that vectors allow expansion without pixelation. Is this the only reason people use Trace Bitmap, so that they can expand the images existing in original bitmaps without loss of quality?

Ps. I know that raster is concerned with bitmaps, and vectors with mathematical expressions

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 Post subject: Re: Trace Bitmap
PostPosted: Fri Oct 31, 2014 12:46 pm  (#5) 
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@avon_private Tracing is being used for different purposes.
Digital artists usually trace bitmaps to integrate images (or its parts) in their art http://wegraphics.net/blog/tutorials/cr ... tle-brush/,
advertisement designers use high-end tracing algorithms (Adobe Illustrator) for vectorising human models,
commercial products, etc. for further use in a variety of formats (pdf, eps for prints/posters, etc.) with
changing resolutions per customer demands.

@ofnuts I wouldn't confine vector graphics just to creating logos, texts and primitive art.
Vector graphics can be very complex and indistinguishable from the photographs or 3D creations http://vectorboom.com/load/articles/ins ... /9-1-0-542


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 Post subject: Re: Trace Bitmap
PostPosted: Fri Oct 31, 2014 3:58 pm  (#6) 
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Expand is not everything. All geometric transforms that do not map pixel for pixel(*) will introduce some blur in bitmap graphics. In the image below, the very same perspective transform has been applied to a bitmap and to the equivalent path (which is then filled). The G gets blurry because it is expanded, but the P which is called down also becomes slightly blurry. No such blur in the path version.

Attachment:
BitmapVsVector.png
BitmapVsVector.png [ 27.62 KiB | Viewed 3731 times ]


(*) About all, except, move, flip, and rotation by a multiple of 90°

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 Post subject: Re: Trace Bitmap
PostPosted: Fri Oct 31, 2014 4:09 pm  (#7) 
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Inkscape's native file SVG is a vector format although it can be a container of raster image data. Bitmap Trace should be used when you plan to alter that data. If you're simply adding a PNG or JPEG to a static SVG canvas Bitmap Trace is not required.

I've attached a SVG that contains vector and raster data. I opened this JPG in Inkscape (the raster data was not altered) and added the stars and text. The image looks good because it still has all the original raster data in a static view. When zooming in or out the vector data stays crisp, only the raster data is slightly distorted. In this case Bitmap Trace was not required because the result is acceptable. If I needed to alter the raster image data (filters, color, etc.) or canvas size later I would have considered using Bitmap Trace first. It's case by case whether you need to use Bitmap Trace or not when adding raster images in Inkscape.


Attachments:
1927-Ford-Model-T-gcx.svg.bz2 [47.99 KiB]
Downloaded 102 times

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 Post subject: Re: Trace Bitmap
PostPosted: Sat Nov 01, 2014 1:18 am  (#8) 
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Odinbc wrote:
Inkscape's native file SVG is a vector format although it can be a container of raster image data. Bitmap Trace should be used when you plan to alter that data. If you're simply adding a PNG or JPEG to a static SVG canvas Bitmap Trace is not required.

I've attached a SVG that contains vector and raster data. I opened this JPG in Inkscape (the raster data was not altered) and added the stars and text. The image looks good because it still has all the original raster data in a static view. When zooming in or out the vector data stays crisp, only the raster data is slightly distorted. In this case Bitmap Trace was not required because the result is acceptable. If I needed to alter the raster image data (filters, color, etc.) or canvas size later I would have considered using Bitmap Trace first. It's case by case whether you need to use Bitmap Trace or not when adding raster images in Inkscape.


Thank you,

Yes, I see what you mean when zooming. I can zoon using the wheel on the mouse. Is there a button that allows continous zooming/reduction? I can't see one!

I get the impression that 'at the end of the day' Trace/or not, or even using Inkscape itself is all dependent on the quality of the final image, after zooming or transforations (ref. Ofnuts).

Best wishes.

A

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OS is Kubuntu
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Processor: Pentium D (2.8GHz)
Video Card: Nvidia GeForce 7300 Turbocache 256MB


Last edited by anon_private on Sat Nov 01, 2014 1:28 am, edited 1 time in total.

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 Post subject: Re: Trace Bitmap
PostPosted: Sat Nov 01, 2014 1:26 am  (#9) 
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ofnuts wrote:
Expand is not everything. All geometric transforms that do not map pixel for pixel(*) will introduce some blur in bitmap graphics. In the image below, the very same perspective transform has been applied to a bitmap and to the equivalent path (which is then filled). The G gets blurry because it is expanded, but the P which is called down also becomes slightly blurry. No such blur in the path version.

Attachment:
BitmapVsVector.png


(*) About all, except, move, flip, and rotation by a multiple of 90°


Ok,

I see what you mean, I need to consider expansions and transforms and the effects of blur in bitmaps vs better defined vector constructions.

_________________
Gimp 2.8.10
Inkscape 0.48
OS is Kubuntu
RAM: 1GB
Processor: Pentium D (2.8GHz)
Video Card: Nvidia GeForce 7300 Turbocache 256MB


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