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For your panoramas: Xpano |
Posted by: Ofnuts - 04-02-2023, 05:07 PM - Forum: Other graphics software
- Replies (11)
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Want to stitch pictures together? Try Xpano (Linux and WIndows version).
Very easy to use. From this:
To this(*):
... in matter of seconds. Only manual intervention: tweak the crop frame (but it automatically determines the biggest frame that fits the stitch, and can even auto-fill corners).
Only two downsides: install appears some what bulky, and JPEG are saved with quartered chroma (but you can saved to PNG).
(*) Image scaled down 50% to fit the forum's file size limits.
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GIF frames deleting script. |
Posted by: rey - 04-02-2023, 12:29 PM - Forum: Scripting questions
- Replies (9)
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I understand it's not polite to bluntly ask for anybody to make a script that i need, so hope asomebody can give hints on commands i must use to try to achieve my goal.
The goal is a a script that makes automatic deletion of GIF frames(layers) based on 2 parameters, and then exports file in original location adding some "copy"/"-01" to name. The deletion logic should work like "delete X frames after each Y frames".
For example:
= GIF with 22 frames, parameters are X=2 Y=3, after processing there will be: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
= GIF with 22 frames, parameters are X=1 Y=4, after processing there will be: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
[crossed frames are deleted]
Hope for your help.
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What is anti-aliasing? |
Posted by: Ofnuts - 04-01-2023, 04:41 PM - Forum: Tutorials and tips
- Replies (1)
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Anti-aliasing is the technique used to obtain lines that are both visually sharp and smooth.
If the smallest "drawable" units (in other words, the pixels) on our displays were smaller that our eyesight resolution, there would be no problem, but with the current display technology they are still somewhat visible, so anti-aliasing is how the problem is mitigated.
Assume that we have a pixel (the whole square) that straddles the edge of an object (red line):
In this pixel, 80% of the pixel is in the object (black), 20% is outside (white)
What should be the color of the pixel?
Well, things shouldn't change with scale, right? So, if we use a bigger object (so, more pixels) and step back so that the visual size is the same as before, the area of the initial pixel is now covered by black pixels and white pixels, where 80% of the pixels are black, and 20% are white (if we forget the pixels along the edge).
What is the color equivalent color? This is the color of an area where 80% of the pixels are black, so for instance this is the perceived color of this (from sufficiently far away):
Which is the same color as this (the image above, with Filters > Blur > Pixelize and a block size equal to the image size).
Note that the "perceptual" channel values of this color are not 20% (or around 50, if using the [0..255] notation), but close to 50% (or 127) because luminosity is not proportional to channel values, due to gamma correction.
And what happens if, instead of colors, we draw on a transparent background? In practice, the problem is very similar, because the transparency of pixels is computed in a very similar way (see the description of the "over" operator), so anti-aliasing uses partial opacity instead of a color blend.
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