errors in bitmap to vector videos

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adze_cnc
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Joined: Sat Jul 27, 2013 10:08 pm
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errors in bitmap to vector videos

Post by adze_cnc »

I've watched a number of "How to convert bitmap to vectors" videos lately and have been non-plussed. The presenters mean well but they commit two "sins" when it comes to the image (a.k.a. raster or bitmap) files:
  1. scale-up and / or rotate image prior to converting it to vectors
  2. saving a smaller-sized image displayed by Google image search (GIS) as the preview of the larger-sized image found on the linked website
The problem with number 1 is two-fold:
  • scaling and / or rotating distorts the bitmap and that loss of fidelity transfers to the resulting vectors
  • unlike Hollywood in which scaling up a bitmap makes it "more in focus" scaling digitally "smears" the image. For example if you have a 10x10 pixel image and each pixel is a different colour (100 in total) which you scale up to 20x20 you will still only have 100 colours but each one of them will be represented by a 2x2 square instead a 1x1 square.
It's far better to create vectors from a small file and scale-up and rotate those vectors. Vectors are made to be transformed without any loss in fidelity.

The problem with number 2 is that the image is not as large as it could be. In one video I watched recently the image at the linked-to site was 1880 pixels wide but the one the presenter saved from the GIS preview was 483 wide. Yet he was sure that he was saving the higher-resolution version.

Sample images to make two points clear:
Small image 92x99
Small image 92x99
butterfly-th.png (15.1 KiB) Viewed 509 times
Small image digitally zoomed by software to 276x297 (note the smeared unfocused appearance caused by replacing each 1x1 pixel with a 3x3 block)
Small image digitally zoomed by software to 276x297 (note the smeared unfocused appearance caused by replacing each 1x1 pixel with a 3x3 block)
Image optically zoomed to 276x297 (same size as previous but much sharper as the pixels haven't been tripled)
Image optically zoomed to 276x297 (same size as previous but much sharper as the pixels haven't been tripled)
In summary:
  • don't scale / rotate images; scale or rotate vectors instead
  • take the time to get the best resolution image you can (go to a linked website or scan at a higher pixel per unit of measure)
  • bonus: avoid jpeg if you can (don't save to this format when scanning)
PS. Vectric's own tutorial video violates point number 1 above.

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highpockets
Vectric Wizard
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Re: errors in bitmap to vector videos

Post by highpockets »

Good tips, thanks for sharing....
John
Maker of Chips

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scotttarnor
Vectric Wizard
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Model of CNC Machine: Piranha XL , Shark HD520
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Re: errors in bitmap to vector videos

Post by scotttarnor »

Thank You for the tips!
Scott T

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