Feature request: Layers

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Thomas Pototschnig

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Nov 19, 2011, 5:33:44 PM11/19/11
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Hi,

I always was missing an image format which allows you to store more
layers of images within one single image container. For instance, 3
JPG-like images (layer 0 - 2), 3 PNG-like images with trancparency (3
- 5).

I know, I could use css-sprites for simulate layering, but it's not
possible to really overlay a JPG-like image with a e.g. transparency
mask without having a second image to load.

I would like to have an image container format which is able to switch
every single layer on or off independantly.

What do you think about?

All the best,
Thomas

Pascal Massimino

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Nov 27, 2011, 4:01:31 PM11/27/11
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Hi Thomas,

on the radar,there's this idea of adding an index chunk to describe some displayable
boxes (or ROI, some may call) extracted from all the images stored in the
RIFF WebP file. This index chunk would map a label to a rectangular area somewhere
amongst the N pictures stored.
Doing so, one could reference the area using: <img src='group.webp#first_layer'>
and  <img src='group.webp#second_layer'> for instance.

The libwebp decoder already has the fast-crop facility, so it's mostly a problem
at muxing/demuxing level now.

skal



All the best,
Thomas

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pik...@gmail.com

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Sep 2, 2013, 4:27:47 AM9/2/13
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2011 two years and no *real* support for layers.
We need a image editor to edit/create this zones.
It would be nice a demo. Because I want to see how does it behave with background repeat, background resize...
This feature (made easy) could be a game changer and help the format to standarize.
Because you save *lot* of bandwidth putting all image style in one file for a website.
And, by the way you could fallback to separate items, because *you reward the browsers that supports webp*

If google really wants to make webp a standard he only should put someone in a complete built in (and full) gimp support. 

oX Triangle

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Sep 2, 2013, 7:50:32 AM9/2/13
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state now. webp 0.31
layer (incremental loading similar jpeg2000) support is coming with 0.4 or 0.5

Pascal Massimino

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Sep 4, 2013, 6:14:05 PM9/4/13
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Hi,

On Mon, Sep 2, 2013 at 1:27 AM, <pik...@gmail.com> wrote:
2011 two years and no *real* support for layers.
We need a image editor to edit/create this zones.
It would be nice a demo. Because I want to see how does it behave with background repeat, background resize...
This feature (made easy) could be a game changer and help the format to standarize.
Because you save *lot* of bandwidth putting all image style in one file for a website.
And, by the way you could fallback to separate items, because *you reward the browsers that supports webp*

it's quite a lot of work _browser_ side. And right now, some priority has been put on finishing
the support for the other features (ICC, metadata, animation) that require some browser-side changes too.
One step at a time... (even if it's a long step!).

That being said, layers could be emulated with animations, since each animation frame can have its own transparency.
But, to remove some layers, you need to edit the raw webp file and remove some frame chunks. Just thinking out loud...

skal
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norman.b...@gmail.com

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Sep 6, 2013, 1:37:42 PM9/6/13
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If we do layers, can we also provide meta data for the alternate text description? I'd dance at somebody's wedding to be able to embed the actual plain text description in a image in such a way that we could use it for alt attributes in web content and elsewhere. There is no reason accessibility (information) should be required to be separate from presentation (the image) in these cases!

oX Triangle

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Sep 7, 2013, 1:14:04 AM9/7/13
to webp-d...@webmproject.org, thomas.po...@lrz.de, norman.b...@gmail.com
btw the webp is free ... u can use very easy own RIFF-Container-Chunks
to handle little info-embed without stops compatiblity on other readers
other readers and converters ignore this chunk


but a standardizated default defination for this info would be nice yes ;-)

Paul A Norman

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Sep 7, 2013, 2:15:35 AM9/7/13
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"embed the actual plain text description in a image in such a way that we could use it for alt attributes in web content"

There seem to have been a number of efforts initiated to read exif (etc!) from html5 Canvas blob in plain JavaScript which may mean that specific native browser implementation(s) may not even be required perhaps? 


Would perhaps lend itself to jQuery (et al) wrappers for titles/alt etc... ?

Paul




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