Limiting multi-layer storage of real data

Limiting multi-layer storage of real data

Post by DaveSenes » Sat, 13 Sep 2003 01:00:16



I edit many large multi hundred megabyte .psd image files.  Am running
Photoshop 6.0.  I have a file storage size issue when saving .psd
files which have multiple layers.  Have looked in the Help infomation
for layers, blending, opacity but did not notice what I need to know.

For my saved .psd image files, I end up with two layers, the bottom
background layer with all the image data and a text layer which may
have non image text information as signature, title, copyright
information etc. Of course I don't wish to combine the two and corrupt
the real image which might be used in other ways cleanly. The amount
of real data on the text layer is insignificant.  When I save such a
file, each layer has similar data storage reserved.  For instance as
an example both the background and text layers would be 200 megabyte
for a total file storage of 400 megabytes.  My usual layer setting is
for 100% opacity and Normal mode.  What I wish to do is set up the
text layer so it stores just the real text information and not storage
for all the unused pixels.   Without such a mode I will be wasting
twice as much on storage media.  Note I tried expirementing with
several of the layer and blending functions without success.  -David

 
 
 

Limiting multi-layer storage of real data

Post by Taci » Sat, 13 Sep 2003 01:31:19


Quote:>The amount
>of real data on the text layer is insignificant.  When I save such a
>file, each layer has similar data storage reserved.  For instance as
>an example both the background and text layers would be 200 megabyte
>for a total file storage of 400 megabytes.

No, that's not what's happening.

A layer which contains a small amount of information, such as text, contributes
only a few kilobytes (at most) to the size of the file.

The file is ending up at 400 MB because you have chosen the option to "Maximize
compatibility" when you saved the file in PSD format.

In English, "Maximize compatibility" means "Flatten the image, save the
flattened version, then save the layered version on top of that." So the image
is being stored in the file TWICE; once flat, and once as layers.

If you turn off the "Maximize compatibility" option when saving a PSD file, the
file will be smaller--in some cases, HALF the size. This option is only useful
if you import the file into programs that understand how to read Photoshop 2.5
files that do not include layers.

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Limiting multi-layer storage of real data

Post by DaveSenes » Mon, 15 Sep 2003 13:19:50


Thanks much tacit.   I may have selected that option when I installed
6.0 as I have a bunch of old PS 3.0 files still on floppies.   Just
spent several hours re-writing image files out and regained about 15gb
storage.

Went back into PS Help and read the too simple info on "file
compatibility".  Also there does not seem to be any information
linking blending and layers back toward that.  Not surprising as
application software help tools for complex applications often have a
some amount of vague lose ends.   Fortunately there is a forum as this
which I can post questions to others with more expertise.  -David


> >The amount
> >of real data on the text layer is insignificant.  When I save such a
> >file, each layer has similar data storage reserved.  For instance as
> >an example both the background and text layers would be 200 megabyte
> >for a total file storage of 400 megabytes.

> No, that's not what's happening.

> A layer which contains a small amount of information, such as text, contributes
> only a few kilobytes (at most) to the size of the file.

> The file is ending up at 400 MB because you have chosen the option to "Maximize
> compatibility" when you saved the file in PSD format.

> In English, "Maximize compatibility" means "Flatten the image, save the
> flattened version, then save the layered version on top of that." So the image
> is being stored in the file TWICE; once flat, and once as layers.

> If you turn off the "Maximize compatibility" option when saving a PSD file, the
> file will be smaller--in some cases, HALF the size. This option is only useful
> if you import the file into programs that understand how to read Photoshop 2.5
> files that do not include layers.

 
 
 

1. Limit Plotted Data by Unplotted Data

Is it possible given a data set such as:

2003-06-20 19:56:36 38.4853 76.3642  0.65   1.00   3.6   340 22.3
2003-06-21 00:51:04 38.4855 76.3642  0.44   0.74   2.9   345 21.8
2003-06-21 02:30:42 38.4853 76.3642  0.58   0.96   3.1   340 21.6

to plot data from columns 4 and 3 excluding those lines where columns 1
& 2 (collectively a date value) fall outside of a range?

I tried this:

plot 'file.dat' using 4:( ( $1 > '2003-07-20 21:21:00' && $1 <
'2003-07-23 21:21:00' ) ? $3 : 1/0)

but to no avail.  Any help would be greatly appreciated.

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