Silly question - again!!

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bruce1951
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Silly question - again!!

Post by bruce1951 » Tue 21 Mar 2017 01:32

Just being lazy and asking here rather than using Mr Google.

I have seen a discussion re layers while using tiffs on one forum. Now it's my understanding that to save all layers in any editor you need to use that editors own format. ie PLD in Photoline. PSPImage in PSP etc etc etc. Tiffs don't support layers.

So my question is - What format are the actual layers? ie when I load a tiff into PL I can duplicate it, adjust it, create new layers etc etc etc, As long as I save it as PL format all is ok. But what if I send one of those layers to an external editor such as PSP? That layer goes to PSP as a tiff? Yes, no? And back to PL, again as a tiff. So does saving a file as a PL file really keep the files as a collection of tiffs or is PL actually changing the layer formats?

Am I making sense? Are the layers within a PL file actually tiffs or some other format?

This is just a search for knowledge and not a 'let me do this' type of question.

regards

bkh
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Re: Silly question - again!!

Post by bkh » Tue 21 Mar 2017 02:10

bruce1951 wrote:
Tue 21 Mar 2017 01:32
Tiffs don't support layers.
Not quite true. TIFFs can store multiple images, and these can be interpreted as multiple layers or multiple pages (the interpretation is not part of the TIFF standard). But TIFFs can't store layer intensities, blend modes, adjustment layers, …
bruce1951 wrote:
Tue 21 Mar 2017 01:32
So does saving a file as a PL file really keep the files as a collection of tiffs or is PL actually changing the layer formats?
No, PLD files usually store their layers in PNG format (you can force JPEG compression, if needed).

But the actual data format doesn't matter as long as compression is lossless – if you open a file, its content is decoded into an uncompressed bitmap image in memory, and when you save the file (or send a layer to an external program) the bitmap gets saved in whatever format is needed. (Sometimes, PL also keeps the compressed data until the layer is changed – this is shown in the layer attributes and may speed up saving files).

Cheers

Burkhard.

bruce1951
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Re: Silly question - again!!

Post by bruce1951 » Tue 21 Mar 2017 03:15

Thanks Burkhard.

Then why do 'most' editors not save the layers when saving as a tiff? Is it simply a matter of developers trying to 'force' you to use their propriety format?

If PL stores the layers as PNG why do I get different results when sending a PNG layer to PSP as opposed to tiffs? (Guessing it's the way PSP handles the layers).

Again thanks. It's always interesting to not only know how to do something but why that something is happening.

regards

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Herbert123
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Re: Silly question - again!!

Post by Herbert123 » Tue 21 Mar 2017 07:45

Blame Adobe for the confusion surrounding layered TIFF files. TIFF was originally owned by Aldus, and when Adobe acquired that company, they also gained control over the TIFF format.

TIFF is a very flexible file format, and supports 'private' tagging to extend the format's capabilities. Adobe extended its use in Photoshop by allowing a fully layered file to be saved in the TIFF - or rather, the entire Photoshop file, because all of Photoshop's special features (layer effects, vector layers, etc.) are all retained when such a layered TIFF file is opened in Photoshop.

But this additional information is either unsupported or only partially processed in other image editors. PhotoLine actually does a pretty good job - but not nearly as good a translation compared to the PSD import.

That's it, really. A layered TIFF saved by Photoshop is more or less a PSD cloaked inside the TIFF file format with a flattened version that can be opened in any image editor/viewer, even though the Photoshop data remains mostly unsupported outside Adobe products.

Aside from this, TIFF also supports an alpha channel and/or a vector (clipping) mask for cutouts.

But never forget that TIFF and PSD are controlled and owned by Adobe - and Adobe made TIFF, which is in theory an open format, partly a closed proprietary format by allowing a PSD to be embedded in it.

More info:
https://en.wikipedia.org/wiki/TIFF
http://www.digitaldog.net/files/TiffvsPSD.pdf
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Hoogo
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Re: Silly question - again!!

Post by Hoogo » Tue 21 Mar 2017 09:51

There's an internal way to look at layers, from programmers point of view.
There you will arrange all the pixels in a way that's best for your program. Could be pixel after pixel, one byte red, one green, one blue, from left to right and top to bottom. But maybe it's more useful for your code to store all reds, then all greens, then all blues? Or cut the layer into tiles of 16*16 pixels and store lots of tiles? Maybe all first pixels of all layers, then all 2nd pixels of all layers? Whatever idea a programmer might have, there's no restriction by standards.

Next there's an external view, how others see the data.
You can have any strange idea how to store your graphics, but you cannot expect that the rest of the world knows about them and that you could just shove your data to another program and expect some useful results.
There's some agreement how the data should look like, so all programs can understand them. Still difficult enough, I've read more than once about problems with alpha here, or with key colors and stuff...
And that's only about the pure pixel content. You could easily invent some new blend mode, or layer properties no one has seen before. PL can distort layers, don't expect to see the same distortion when you send the layer to PSP. You just cannot place that information in the agreed format.

Finally there's tiff
It's more like a ZIP file, you can store layers and anything in it as you can store different files in a Zip.
And there are lots of agreements about the format of "layers" in a tiff, just like .doc, .xls, .txt are formats in a Zip that make sense to anyone.
You can really stro anything in a tiff, just liek you could store a .xyz in a Zip. Doesn't mean that anybody except yourself knows how to treat a .xyz-file...
There are even some holes in the definition of tiff, as mentioned. 2 graphics in it: Are these 2 layers? 2 pages? 1 graphic and a rescaled preview?
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bkh
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Re: Silly question - again!!

Post by bkh » Tue 21 Mar 2017 12:53

bruce1951 wrote:
Tue 21 Mar 2017 03:15
Then why do 'most' editors not save the layers when saving as a tiff?
Because there is no standard way to interpret these layers (actually, it's just several images in a single tif file). If program A saves a tiff and needs to be sure that it can be opened/edited in program B, the only safe way is to save just a single image in the tif file. Apart from this, there are two common interpretations of multiple images in a tiff: layers or pages. PL lets you choose which of the two to use (and you'll have to make a corresponding choice when using the tiff in another program).
bruce1951 wrote:
Tue 21 Mar 2017 03:15
Is it simply a matter of developers trying to 'force' you to use their propriety format?
No, as a developer you'll effectively need a proprietary format to be able to save all the features that your program has. Even Adobe, though in control of TIFF, DNG and PDF, has their own proprietary formats because (1) adding new features is easier, no other program needs to adopt them first and (2) you don't have to publish the underlying algorithms.

Cheers

Burkhard.

bruce1951
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Re: Silly question - again!!

Post by bruce1951 » Tue 21 Mar 2017 14:25

Thanks everyone. I've now replaced some old unused brain cells with some interesting information.
Never tooooo old to learn.

regards

borgo1971
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Re: Silly question - again!!

Post by borgo1971 » Tue 04 Feb 2020 16:28

bkh wrote:
Tue 21 Mar 2017 02:10
No, PLD files usually store their layers in PNG format (you can force JPEG compression, if needed).
How can I do this? :?: