[Cin] worse zoom quality when original foto is big

[Phyllis Smith]

It is not clear what the actual problem is.  Many camera images may have a
high pixel
count, but not be effectively coded.  What is normally displayed on the
composer window
is directly traceable to the codec output.  There are a few exceptions, and
using a plugin
like autoscale is one of them.  The preferences can affect the scaling
equations.  See:
Preferences->Playback A->Scaling Equation->Popup (Nearest...Lanczos)

Normally, the scaling is nearest neighbor, since it is fastest.  But if you
want the buffer
to be filtered on scaling, there are a whole bunch of plugins which claim
to be good at
doing just that.   When you zoom in, normally the composer canvas is
smaller than the
media buffer dimensions.  Once the magnification makes the pixel to pixel
mapping
better than unity, you see square pixels.  There is no such thing as the
NCIS effect that
lets you magnify one pixel into and entire licence plate.  If the data is
not there, it cannot
be magnified or filtered.

I did try to test this, and the results looked predictable.  I have
attached the results.
This is a wallpaper picture downloaded from:
https://images.wallpaperscraft.com/image/autumn_forest_trees_80863_4000x3000.jpg
I loaded it, and set the format to 1920x1080, added "Auto Scale" plugin,
and setup its
scaling parameters.  This plugin uses the preference scaling equations.

The attachments are:
auto zoom, nearest neighbor, still crispy little branches
zoom x 8.9, nearest neighbor, pixels are too crispy
zoom x 8.9, bicubic,bicubic, better
zoom x 8.9, linear,linear, best I think, no halos
zoom x 8.9, lanczos, pretty good, but I like linear

I do not see any macropixel artifacts, or boundary problems.  If you see a
problem, or
can demonstrate a problem with some media you can provide, please let us
know and
I will definitely give it a look.

Thanks for your attention,
gg




On Tue, Mar 3, 2020 at 4:05 AM deim31 <deim31 at gmail.com> wrote:

> Hi, I noticed when I paste e.g. 12 MPx photo - and video output is e.g.
> 720p or 1080p the quality of zoomed-out photos is somehow bad - when I
> use Scale or Auto Scale the result was worse than camera automation but
> either result wasn't in good quality.
>
> Thanks,
> deim
>
> --
> Cin mailing list
> Cin at lists.cinelerra-gg.org
> https://lists.cinelerra-gg.org/mailman/listinfo/cin
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cinelerra-gg.org/pipermail/cin/attachments/20200303/51b1917d/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: linear.png
Type: image/png
Size: 37008 bytes
Desc: not available
URL: <https://lists.cinelerra-gg.org/pipermail/cin/attachments/20200303/51b1917d/attachment-0005.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: nearest.png
Type: image/png
Size: 40516 bytes
Desc: not available
URL: <https://lists.cinelerra-gg.org/pipermail/cin/attachments/20200303/51b1917d/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: autoscale.png
Type: image/png
Size: 1026909 bytes
Desc: not available
URL: <https://lists.cinelerra-gg.org/pipermail/cin/attachments/20200303/51b1917d/attachment-0007.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: lanczos.png
Type: image/png
Size: 39136 bytes
Desc: not available
URL: <https://lists.cinelerra-gg.org/pipermail/cin/attachments/20200303/51b1917d/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: bicubic.png
Type: image/png
Size: 38234 bytes
Desc: not available
URL: <https://lists.cinelerra-gg.org/pipermail/cin/attachments/20200303/51b1917d/attachment-0009.png>