Image / Bitmap Scale

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andrew
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Image / Bitmap Scale

Post by andrew » Mon Jun 27, 2016 10:47 am

What is a Bitmap?

Bitmaps are images represented by small square-shaped dots called "pixels". For example a bitmap with a size of 800x600 pixels consists of 800x600 small squares with different colors. The size of such a square or pixel is not universally defined and depends on what device the bitmap is displayed and how it is scaled up or down.

When inserting a bitmap into a CAD system (for example for tracing or vectorization), the scale (and often also the angle) of the bitmap have to be adjusted accordingly. There are several ways to achieve this in QCAD.

Defining the Size while Inserting the Bitmap

You can set the desired width or height of the inserted bitmap while inserting the image in the options tool bar at the top:
Screen Shot 2016-06-27 at 11.44.24.png
Screen Shot 2016-06-27 at 11.44.24.png (19.36 KiB) Viewed 6996 times
See also reference manual for Draw > Insert Bitmap.

Scaling a Bitmap

After inserting a bitmap, you can scale it just like any other entity using Modify > Scale.

Adjusting the Bitmap Size in the Property Editor

You can also set the image width or height in the property editor (View > Property Editor):
Screen Shot 2016-06-27 at 11.46.22.png
Screen Shot 2016-06-27 at 11.46.22.png (87.95 KiB) Viewed 6996 times
Aligning a Bitmap

If you know the size of at least one particular feature in your bitmap or a distance in your bitmap, you can align (rotate and scale) your bitmap using Modify > Align Reference Points.

Situation after inserting the bitmap and click points for the align reference points tool:
Screen Shot 2016-11-22 at 13.58.01.png
Screen Shot 2016-11-22 at 13.58.01.png (96.69 KiB) Viewed 6562 times
Result:
Screen Shot 2016-11-22 at 13.58.58.png
Screen Shot 2016-11-22 at 13.58.58.png (47.49 KiB) Viewed 6562 times

Kowal
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Joined: Sat Nov 18, 2017 11:23 am

Re: Image / Bitmap Scale

Post by Kowal » Tue Nov 21, 2017 3:01 pm

Thanks for the tutorial Andrew! I'm learning about scale at the moment so this was helpful.

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