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I am reworking an old globe of the Earth and I see that I used a cloud
map image with 4 bit colour depth. So that I could manage the
transparency (only 16 pallet entries).
It was okay for a small image but now I want something with more
resolution.
Any suggestions?
--
Regards
Stephen
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On 26-11-2014 12:36, Stephen wrote:
> I am reworking an old globe of the Earth and I see that I used a cloud
> map image with 4 bit colour depth. So that I could manage the
> transparency (only 16 pallet entries).
> It was okay for a small image but now I want something with more
> resolution.
> Any suggestions?
>
Could you use this?
http://www.shadedrelief.com/natural3/pages/clouds.html
Thomas
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On 26/11/2014 12:45, Thomas de Groot wrote:
> On 26-11-2014 12:36, Stephen wrote:
>> I am reworking an old globe of the Earth and I see that I used a cloud
>> map image with 4 bit colour depth. So that I could manage the
>> transparency (only 16 pallet entries).
>> It was okay for a small image but now I want something with more
>> resolution.
>> Any suggestions?
>>
>
> Could you use this?
>
> http://www.shadedrelief.com/natural3/pages/clouds.html
>
> Thomas
I am or something like it.
My understanding is that PovRay uses either an alpha channel or a pallet
based transparency. With the pallet based method 256 channels are the
most you can use. I was hoping that someone had devised a way to use the
greyscale value.
I have an acceptable result by converting the original image to 8 bit
and blurring it a small bit. Then inputing the pallet entries by hand.
Or by Excel, actually. :-)
--
Regards
Stephen
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On 26-11-2014 14:12, Stephen wrote:
> On 26/11/2014 12:45, Thomas de Groot wrote:
>> On 26-11-2014 12:36, Stephen wrote:
>>> I am reworking an old globe of the Earth and I see that I used a cloud
>>> map image with 4 bit colour depth. So that I could manage the
>>> transparency (only 16 pallet entries).
>>> It was okay for a small image but now I want something with more
>>> resolution.
>>> Any suggestions?
>>>
>>
>> Could you use this?
>>
>> http://www.shadedrelief.com/natural3/pages/clouds.html
>>
>> Thomas
>
> I am or something like it.
> My understanding is that PovRay uses either an alpha channel or a pallet
> based transparency. With the pallet based method 256 channels are the
> most you can use. I was hoping that someone had devised a way to use the
> greyscale value.
>
> I have an acceptable result by converting the original image to 8 bit
> and blurring it a small bit. Then inputing the pallet entries by hand.
> Or by Excel, actually. :-)
>
What is a pallet-based transparency? The term is unfamiliar to me.
Thomas
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On 26/11/2014 15:02, Thomas de Groot wrote:
> What is a pallet-based transparency? The term is unfamiliar to me.
Not surprised. I made it up.
From the top of my head:
It is an index of colours used in the image. In Pov we can set the
transparency and filter values in the image_map definition. Each entry
in the index can be set to a transparency, individually. I think that
pallet based images are limited to 8 bit images.
So in a cloud map each grey could have a different level of transparency.
rgb -> rgbft
--
Regards
Stephen
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Stephen <mca### [at] aol com> wrote:
> I am or something like it.
> My understanding is that PovRay uses either an alpha channel or a pallet
> based transparency. With the pallet based method 256 channels are the
> most you can use.
Are you using image_pattern and/or use_alpha?
> I was hoping that someone had devised a way to use the
> greyscale value.
I sort of see what you want to do...
Maybe you could "scan" the image with eval_pigment and then calculate a
transparency variable using the grayscale value?
I dunno - I'm still only on coffee #2, and the foot of snow we're supposed to be
getting is just starting to come down, so I'm not 100% focused...
> I have an acceptable result by converting the original image to 8 bit
> and blurring it a small bit. Then inputing the pallet entries by hand.
> Or by Excel, actually. :-)
That sounds somewhat labor intensive, though interesting.
Maybe some example code and a small illustrative image would help puzzle out a
solution.
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On 26/11/2014 16:10, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>
>> I am or something like it.
>> My understanding is that PovRay uses either an alpha channel or a pallet
>> based transparency. With the pallet based method 256 channels are the
>> most you can use.
>
> Are you using image_pattern and/or use_alpha?
>
I am using image_map
>> I was hoping that someone had devised a way to use the
>> greyscale value.
>
> I sort of see what you want to do...
> Maybe you could "scan" the image with eval_pigment and then calculate a
> transparency variable using the grayscale value?
>
LOL
You might be able to do that. I couldn't code my way out of a wet paper
bag. ;-)
I use a modeller for everything. I can modify and add code, though.
> I dunno - I'm still only on coffee #2, and the foot of snow we're supposed to be
> getting is just starting to come down, so I'm not 100% focused...
>
Excuses, excuses. I've been up for eleven hours, allready. ;-)
>> I have an acceptable result by converting the original image to 8 bit
>> and blurring it a small bit. Then inputing the pallet entries by hand.
>> Or by Excel, actually. :-)
>
> That sounds somewhat labor intensive, though interesting.
>
Yes it is. :-(
But I have automated a lot of it in Excel and I copy and paste into the
modeller.
> Maybe some example code and a small illustrative image would help puzzle out a
> solution.
>
I'll make up a little package including the transparency map, later. But
you could use one of the ones Thomas pointed to.
The basic material is:
#declare CloudedEarth =
texture {
#declare BISHOP3D_TEMPORARY_IDENTIFIER =
texture {
pigment {
image_map{
png "f:\Graphics\B3D Data\Maps\Planets\Earth\EarthMap2.png"
/*
This is the image map of Earth.
*/
interpolate 4
map_type 1
}
}
normal {
bump_map{
png "f:\Graphics\B3D Data\Maps\Planets\Earth\EarthBum_Neg.png"
/*
This is the bmp map of Earth.
*/
interpolate 2
use_color
map_type 1
}
0.100 }
}
texture {
pigment {
image_map{
png "F:\Graphics\B3D
Data\Maps\Planets\Earth\earthcloudmaptrans_Neg240.png"
/*
This is the cloud map that I want the dark parts transparent.
*/
interpolate 2
map_type 1
transmit 0, 1.000
transmit 1, 1.000
// Snip lots of entries
transmit 238, 0.007
transmit 239, 0.000
}
}
}
;// the semicolon is necessary or POV-Ray will not figure out that
the declarations has ended
BISHOP3D_TEMPORARY_IDENTIFIER
}
--
Regards
Stephen
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Am 26.11.2014 14:12, schrieb Stephen:
> ... I was hoping that someone had devised a way to use the
> greyscale value.
>
#declare PP_Claud = pigment{image_map{jpeg "my_cloud_map" map_type 1
interpolate 2}}
sphere{ 0, 1.005
texture {
pigment_pattern{PP_Claud}
texture_map {
[0.00 texture {pigment{rgb 1 transmit 1} finish{diffuse 1}}]
[1.00 texture {pigment{rgb 1 transmit 0} finish{diffuse 1}}]
}
}
}
...where "my_cloud_map" is a grayscale, not a color palette image!
and it might be a good idea to add the cloud texture to a slightly
larger scaled sphere (than the planet) and not as top layered texture as
you did.
And you didn't ask for it but anyway: adding a specular map in pretty
much the same way (giving highlights to the ocean covered area but not
to the land mass) makes it even more realistic.
You can obtain maps for this e.g. from NASA's Blue Marble page.
With some scattering media atmosphere it gives something like this:
http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
-Ive
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On 26/11/2014 18:54, Ive wrote:
>
> With some scattering media atmosphere it gives something like this:
> http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
>
Before I look at your suggestions. The above link only goes to the index.
And thanks for the reply
--
Regards
Stephen
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Am 26.11.2014 20:16, schrieb Stephen:
> On 26/11/2014 18:54, Ive wrote:
>>
>> With some scattering media atmosphere it gives something like this:
>> http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
>>
>>
> Before I look at your suggestions. The above link only goes to the index.
>
> And thanks for the reply
>
this should do
http://news.povray.org/povray.binaries.images/message/<4a056976@news.povray.org>/<4a056976@news.povray.org>
-Ive
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On 26-11-2014 19:54, Ive wrote:
> texture_map {
> [0.00 texture {pigment{rgb 1 transmit 1} finish{diffuse 1}}]
> [1.00 texture {pigment{rgb 1 transmit 0} finish{diffuse 1}}]
> }
Nitpicking, but above should be:
texture_map {
[0.00 pigment{rgb 1 transmit 1} finish{diffuse 1}]
[1.00 pigment{rgb 1 transmit 0} finish{diffuse 1}]
}
This discussion reminded me suddenly of a scene I made in 2011 (Port of
Call). I had the clouds not exactly right back then because I failed to
use a pigment_pattern.
I'll post a new version in p.b.i once the scene has finished rendering.
Thomas
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On 27/11/2014 08:58, Thomas de Groot wrote:
> On 26-11-2014 19:54, Ive wrote:
>> texture_map {
>> [0.00 texture {pigment{rgb 1 transmit 1} finish{diffuse 1}}]
>> [1.00 texture {pigment{rgb 1 transmit 0} finish{diffuse 1}}]
>> }
>
> Nitpicking, but above should be:
>
> texture_map {
> [0.00 pigment{rgb 1 transmit 1} finish{diffuse 1}]
> [1.00 pigment{rgb 1 transmit 0} finish{diffuse 1}]
> }
>
I was going to mention that on my next post.
Interestingly, Bishop3D parsed it correctly.
> This discussion reminded me suddenly of a scene I made in 2011 (Port of
> Call). I had the clouds not exactly right back then because I failed to
> use a pigment_pattern.
>
> I'll post a new version in p.b.i once the scene has finished rendering.
>
Be careful. Once you start looking at old scenes. You will find
something else that wants improving. Never ending.
I noticed that some of my earth maps go back to 98 (when I downloaded
them) and the ones I normally use are from 2008. So I downloaded some of
the Blue Marble ones. Now the Nautilus model does not fit in with the
Earth . I will need to rework its textures.
--
Regards
Stephen
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On 27-11-2014 11:55, Stephen wrote:
> Be careful. Once you start looking at old scenes. You will find
> something else that wants improving. Never ending.
> I noticed that some of my earth maps go back to 98 (when I downloaded
> them) and the ones I normally use are from 2008. So I downloaded some of
> the Blue Marble ones. Now the Nautilus model does not fit in with the
> Earth . I will need to rework its textures.
>
>
I know. It is a difficult to resist temptation.
Thomas
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On 27/11/2014 12:15, Thomas de Groot wrote:
> On 27-11-2014 11:55, Stephen wrote:
>
>> Be careful. Once you start looking at old scenes. You will find
>> something else that wants improving. Never ending.
>> I noticed that some of my earth maps go back to 98 (when I downloaded
>> them) and the ones I normally use are from 2008. So I downloaded some of
>> the Blue Marble ones. Now the Nautilus model does not fit in with the
>> Earth . I will need to rework its textures.
>>
>>
> I know. It is a difficult to resist temptation.
>
Not for me. I don't even bother.
See a temptation and pick it up.
And all day you'll have something to do.
And I have a new PC which goes Varoom!
--
Regards
Stephen
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On 27-11-2014 13:47, Stephen wrote:
> On 27/11/2014 12:15, Thomas de Groot wrote:
>> On 27-11-2014 11:55, Stephen wrote:
>>
>>> Be careful. Once you start looking at old scenes. You will find
>>> something else that wants improving. Never ending.
>>> I noticed that some of my earth maps go back to 98 (when I downloaded
>>> them) and the ones I normally use are from 2008. So I downloaded some of
>>> the Blue Marble ones. Now the Nautilus model does not fit in with the
>>> Earth . I will need to rework its textures.
>>>
>>>
>> I know. It is a difficult to resist temptation.
>>
>
> Not for me. I don't even bother.
> See a temptation and pick it up.
> And all day you'll have something to do.
>
> And I have a new PC which goes Varoom!
>
>
LOL Excellent!
Thomas
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On 26/11/2014 18:54, Ive wrote:
> Am 26.11.2014 14:12, schrieb Stephen:
>> ... I was hoping that someone had devised a way to use the
>> greyscale value.
>>
>
>
Thanks, I posted an update in p.b.i in Thomas's thread.
> #declare PP_Claud = pigment{image_map{jpeg "my_cloud_map" map_type 1
> interpolate 2}}
>
> sphere{ 0, 1.005
> texture {
> pigment_pattern{PP_Claud}
> texture_map {
> [0.00 texture {pigment{rgb 1 transmit 1} finish{diffuse 1}}]
> [1.00 texture {pigment{rgb 1 transmit 0} finish{diffuse 1}}]
> }
> }
> }
>
> ....where "my_cloud_map" is a grayscale, not a color palette image!
>
> and it might be a good idea to add the cloud texture to a slightly
> larger scaled sphere (than the planet) and not as top layered texture as
> you did.
Yes that is better.
> And you didn't ask for it but anyway: adding a specular map in pretty
> much the same way (giving highlights to the ocean covered area but not
> to the land mass) makes it even more realistic.
What do you know, it makes quite an improvement. The Greek Isles look
very attractive at this time of year.
> With some scattering media atmosphere it gives something like this:
> http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
>
>
I don't want it to look that good. :-)
--
Regards
Stephen
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On 27/11/14 12:47, Stephen wrote:
>
> And I have a new PC which goes Varoom!
>
Are you sure it's meant to make that noise?
John
--
Protect the Earth
It was not given to you by your parents
You hold it in trust for your children
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On 27/11/2014 13:01, Doctor John wrote:
> On 27/11/14 12:47, Stephen wrote:
>>
>> And I have a new PC which goes Varoom!
>>
>
> Are you sure it's meant to make that noise?
>
It's like Mr McHenry on speed. :-D
--
Regards
Stephen
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On 27/11/14 13:14, Stephen wrote:
>
> It's like Mr McHenry on speed. :-D
>
Excellent mental image :-D
John
--
Protect the Earth
It was not given to you by your parents
You hold it in trust for your children
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On 27/11/2014 13:20, Doctor John wrote:
> On 27/11/14 13:14, Stephen wrote:
>>
>> It's like Mr McHenry on speed. :-D
>>
>
> Excellent mental image :-D
>
It is, isn't it?
How about:
Zebedee is on the sex register?
Florence dobbed him in.
(That should keep you awake at nights.) :-P
--
Regards
Stephen
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On 27/11/14 13:37, Stephen wrote:
> How about:
> Zebedee is on the sex register?
> Florence dobbed him in.
>
> (That should keep you awake at nights.) :-P
>
I'm getting increasingly worried about your mental state, young man. ;-)
Now it's time for me to head over the river to attend a pointless meeting.
John
--
Protect the Earth
It was not given to you by your parents
You hold it in trust for your children
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On 27/11/2014 13:52, Doctor John wrote:
> I'm getting increasingly worried about your mental state, young man.;-)
>
> Now it's time for me to head over the river to attend a pointless meeting.
The stews, again?
--
Regards
Stephen
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Am 26.11.2014 16:34, schrieb Stephen:
> On 26/11/2014 15:02, Thomas de Groot wrote:
>> What is a pallet-based transparency? The term is unfamiliar to me.
>
> Not surprised. I made it up.
>
> From the top of my head:
> It is an index of colours used in the image. In Pov we can set the
> transparency and filter values in the image_map definition. Each entry
> in the index can be set to a transparency, individually. I think that
> pallet based images are limited to 8 bit images.
> So in a cloud map each grey could have a different level of transparency.
>
> rgb -> rgbft
Actually, with palette-based images you are limited to 1 bit of
transparency: On or off. Because there's just one special colour among
the 256 that denotes a transparent pixel.
Images with alpha channel (usually png) typically give you 8 bit of
transparency information. If you need more, you can opt for one of the
following:
A) 16-bit png images with alpha channel.
B) pigment_map, using the image's greyscale value to choose between an
opaque and a transparent pigment. (Make sure to set a proper "gamma"
parameter!). However, this will typically give you not much more than 8
bit either, so you'll want to go for 16-bit images anyway.
C) high dynamic range images; OpenEXR can support an alpha channel,
alternatively you can use pigment_map as described above. However, near
100% its precision is a good deal less than that of 16-bit images
(comparable to 12-bit images; Radiance HDR is even worse).
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Am 26.11.2014 20:16, schrieb Stephen:
> On 26/11/2014 18:54, Ive wrote:
>>
>> With some scattering media atmosphere it gives something like this:
>> http://news.povray.org/povray.binaries.images/thread/<4a056976@news.povray.org>
>>
>>
> Before I look at your suggestions. The above link only goes to the index.
The plain text is fine, it's just the link behind it that's broken.
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On 28/11/2014 12:24, clipka wrote:
> Actually, with palette-based images you are limited to 1 bit of
> transparency: On or off. Because there's just one special colour among
> the 256 that denotes a transparent pixel.
>
> Images with alpha channel (usually png) typically give you 8 bit of
> transparency information. If you need more, you can opt for one of the
> following:
>
> A) 16-bit png images with alpha channel.
>
> B) pigment_map, using the image's greyscale value to choose between an
> opaque and a transparent pigment. (Make sure to set a proper "gamma"
> parameter!). However, this will typically give you not much more than 8
> bit either, so you'll want to go for 16-bit images anyway.
>
> C) high dynamic range images; OpenEXR can support an alpha channel,
> alternatively you can use pigment_map as described above. However, near
> 100% its precision is a good deal less than that of 16-bit images
> (comparable to 12-bit images; Radiance HDR is even worse).
Thanks Clipka, I thought that I was finished with this. But what you've
written need digesting. :-)
I must find another editor I've been using PaintShop Pro out of "it's
good enough and I've always used it". What you can do with pallets and
Alpha is basic.
Interestingly the 24 bit Tiff Cloud Map, I downloaded from Blue Marble.
Has only 253 different colours.
--
Regards
Stephen
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Thomas de Groot <tho### [at] degrootorg> wrote:
> On 27-11-2014 11:55, Stephen wrote:
>
> > Be careful. Once you start looking at old scenes. You will find
> > something else that wants improving. Never ending.
> > I noticed that some of my earth maps go back to 98 (when I downloaded
> > them) and the ones I normally use are from 2008. So I downloaded some of
> > the Blue Marble ones. Now the Nautilus model does not fit in with the
> > Earth . I will need to rework its textures.
> >
> >
> I know. It is a difficult to resist temptation.
>
> Thomas
Having fun and "resting" my brain scrolling through
https://www.google.co.uk/search?q=site:news.povray.org&tbm=isch
and I came across this:
http://news.povray.org/povray.binaries.images/attachment/%3C43e348c8%40news.povray.org%3E/Alien%20Cliff.jpg?ttop=284089
&toff=1600
Which instantly meshed with a scene in the book I'm (finally) reading - "Against
All Things Ending" by Stephen Donaldson, where Linden Avery beholds Landsdrop:
"And she caught sight of Landsdrop. Grey in the depthless sunlight, it loomed
two thousand feet and more above her own elevation: a blunt rampart smoothed by
the ages until it appeared almost blank; too sheer to scale. But she knew from
old experience as well as from tales that Landsdrop was more accessible than it
looked. There were trails of all kinds up and down the precipice, although she
could not descry them at this distance. Ignoring the impatience of the Ranyhyn,
Linden studied the vista. Almost directly to the west, a thin string of water
fell as though it had been tossed over the rim by a negligent hand. Dull against
the dim stone, like a strand of tarnished silver, it dropped in stages, shifting
from side to side as its plunge encountered obstacles, and casting fine hints of
spray into the etiolated sunshine."
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On 27/11/14 14:10, Stephen wrote:
>
> The stews, again?
>
How well you know me, young man :-p
John
--
Protect the Earth
It was not given to you by your parents
You hold it in trust for your children
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On 28/11/2014 20:58, Doctor John wrote:
> On 27/11/14 14:10, Stephen wrote:
>>
>> The stews, again?
>>
>
> How well you know me, young man :-p
>
I didn't until you admitted it. :-P
--
Regards
Stephen
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On 28-11-2014 20:16, Bald Eagle wrote:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> On 27-11-2014 11:55, Stephen wrote:
>>
>>> Be careful. Once you start looking at old scenes. You will find
>>> something else that wants improving. Never ending.
>>> I noticed that some of my earth maps go back to 98 (when I downloaded
>>> them) and the ones I normally use are from 2008. So I downloaded some of
>>> the Blue Marble ones. Now the Nautilus model does not fit in with the
>>> Earth . I will need to rework its textures.
>>>
>>>
>> I know. It is a difficult to resist temptation.
>>
>> Thomas
>
> Having fun and "resting" my brain scrolling through
> https://www.google.co.uk/search?q=site:news.povray.org&tbm=isch
>
> and I came across this:
>
>
http://news.povray.org/povray.binaries.images/attachment/%3C43e348c8%40news.povray.org%3E/Alien%20Cliff.jpg?ttop=284089
> &toff=1600
>
> Which instantly meshed with a scene in the book I'm (finally) reading - "Against
> All Things Ending" by Stephen Donaldson, where Linden Avery beholds Landsdrop:
>
> "And she caught sight of Landsdrop. Grey in the depthless sunlight, it loomed
> two thousand feet and more above her own elevation: a blunt rampart smoothed by
> the ages until it appeared almost blank; too sheer to scale. But she knew from
> old experience as well as from tales that Landsdrop was more accessible than it
> looked. There were trails of all kinds up and down the precipice, although she
> could not descry them at this distance. Ignoring the impatience of the Ranyhyn,
> Linden studied the vista. Almost directly to the west, a thin string of water
> fell as though it had been tossed over the rim by a negligent hand. Dull against
> the dim stone, like a strand of tarnished silver, it dropped in stages, shifting
> from side to side as its plunge encountered obstacles, and casting fine hints of
> spray into the etiolated sunshine."
>
And yet, it was not inspired by Donaldson... :-) It was by another SF
world: Mount Lookitthat on Plateau, imagined by Larry Niven. The concept
then drifted slowly away from there to the present image.
Thomas
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On 28-11-2014 13:24, clipka wrote:
> A) 16-bit png images with alpha channel.
>
Which reminds me: Using IC, how can one convert an 8-bit png into a
16-bit png? I suppose the image needs to be resampled but with what
settings?
Thomas
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Le 14-11-29 07:18, Thomas de Groot a écrit :
> On 28-11-2014 13:24, clipka wrote:
>> A) 16-bit png images with alpha channel.
>>
>
> Which reminds me: Using IC, how can one convert an 8-bit png into a
> 16-bit png? I suppose the image needs to be resampled but with what
> settings?
>
> Thomas
>
>
Using most image procesing tools supporting saving PNG with multiple bit
per channel:
Load the original image whitch can be in any format, not just PNG.
Save it as a 16 bit per channel PNG file.
The only thing been that the lower 8 bits will be patched with zeros.
This may be aleviated by enlarging the image and bluring the enlarged
version. This may force some interpolation between the original pixels.
Far from perfect, but beter than nothing.
If you can render the image in POV-Ray, add +fn16 to the command line to
create the image as a 16 bit per channel PNG.
You may try rendering the original image as an image_map of at least
twice the pixel size of the original and use one of the interpolation
methods.
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Am 29.11.2014 13:18, schrieb Thomas de Groot:
> On 28-11-2014 13:24, clipka wrote:
>> A) 16-bit png images with alpha channel.
>>
>
> Which reminds me: Using IC, how can one convert an 8-bit png into a
> 16-bit png? I suppose the image needs to be resampled but with what
> settings?
>
> Thomas
>
>
image->mode->16bps
then save as PNG
this makes only sense if you are going to resize, tonemap, filter, do
*anything* with the image afterwards.
-Ive
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Am 30.11.2014 01:44, schrieb Alain:
> The only thing been that the lower 8 bits will be patched with zeros.
err, no, any decent image processing tool will multiply by 257 instead a
simple left-shift.
-Ive
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On 30-11-2014 11:42, Ive wrote:
> Am 29.11.2014 13:18, schrieb Thomas de Groot:
>> On 28-11-2014 13:24, clipka wrote:
>>> A) 16-bit png images with alpha channel.
>>>
>>
>> Which reminds me: Using IC, how can one convert an 8-bit png into a
>> 16-bit png? I suppose the image needs to be resampled but with what
>> settings?
>>
>> Thomas
>>
>>
>
> image->mode->16bps
>
> then save as PNG
>
> this makes only sense if you are going to resize, tonemap, filter, do
> *anything* with the image afterwards.
>
> -Ive
Yes! You confirm what I suspected already (but was not sure). With only
using mode->16bps, nothing happens. Thanks indeed.
Thomas
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Le 14-11-30 05:47, Ive a écrit :
> Am 30.11.2014 01:44, schrieb Alain:
>> The only thing been that the lower 8 bits will be patched with zeros.
>
> err, no, any decent image processing tool will multiply by 257 instead a
> simple left-shift.
>
> -Ive
>
That 8 bits left shift or multiply by 256 is exactly the same as left
padding with zeros.
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Am 30.11.2014 19:09, schrieb Alain:
> Le 14-11-30 05:47, Ive a écrit :
>> Am 30.11.2014 01:44, schrieb Alain:
>>> The only thing been that the lower 8 bits will be patched with zeros.
>>
>> err, no, any decent image processing tool will multiply by 257 instead a
>> simple left-shift.
>>
>> -Ive
>>
> That 8 bits left shift or multiply by 256 is exactly the same as left
> padding with zeros.
257 != 256
-Ive
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