Hi all,
consider the following example (print it):
"Example 1"
f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 2. g colorAt: 0 @ 0
Expected output: Color red.
Actual output: Color black!
Other examples:
"Example 2"
f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
"Example 3"
f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.973 g: 0.0 b: 0.0)"
I am not familiar with color depths, but afaik Color red could be stored exactly using only 1 bit? Do I misunderstand the concept or is this really a bad output?
(I came across to this when performing #collectColors: on an 8 bit ColorForm loaded from disk, which did not work as expected.)
Best, Christoph
Hi Christoph,
On 09.09.2019, at 13:25, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi all,
consider the following example (print it):
"Example 1" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 2. g colorAt: 0 @ 0
Expected output: Color red. Actual output: Color black!
No, Forms of depth 1 are black and white, and of depth2 are gray.
Other examples:
"Example 2" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
yes, because you go from black/white to 32bit. I would have expected r0g0b0, but there might some rounding go on.
"Example 3" f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.973 g: 0.0 b: 0.0)"
Something's wonky here! If we do
(((Form extent: 1 asPoint depth: 16) colorAt: 0 @ 0 put: Color red) asFormOfDepth: 32) pixelValueAt: 0@0
we get 4294443008 (aka 0xFFF80000) which is a 32bit value. But the meaning is
11111111 11111000 00000000 00000000 ^ alpha ^ r ^ g ^ b
which means that the r component is not "upscaled" during the #asFormOfDepth: process o.O (see PS)
I am not familiar with color depths, but afaik Color red could be stored exactly using only 1 bit? Do I misunderstand the concept or is this really a bad output?
No, the first bit depth to support red is 4 bit.
Have a look at Color class>>colorFromPixelValue: p depth: d
BTW: You can use a ColorForm to work with your own palette, so that you can have for example a 1-bit form with 1=yellow & 0=red…
Best regards -Tobias
(I came across to this when performing #collectColors: on an 8 bit ColorForm loaded from disk, which did not work as expected.)
Best, Christoph
PS: PS: Color red is r:1.0 g:0.0 b:0.0 but stored in a different fashion:
Color comment: " Think of Color's instance variables as: r amount of red, a Float between 0.0 and 1.0. g amount of green, a Float between 0.0 and 1.0. b amount of blue, a Float between 0.0 and 1.0. (But, in fact, the three are encoded as values from 0 to 1023 and combined in a single integer, rgb. The user does not need to know this.) " that means "Color red" is stored as 0x3FF00000 or,
1111111111 0000000000 0000000000 ^ red ^ green ^ blue
that makes 10 bit per component.
However, in the 16 bit form we have only 5 bit per component, so,
f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. f pixelValueAt: 0@0.
yields 0x7C00 aka
11111 00000 00000 ^ r ^ g ^ b
Hi Tobias,
oops, I mistook the depth with the number of bits per channel. Sorry and many thanks for your explanations!
How would one fix the upscaling issue? Form>>#colormapIfNeededFor: returns nil in example 3, the comment in Color>>#colorMapIfNeededFrom:to: states this task is delegated to BitBlt. Is this comment wrong or is the defect in the primitive called that is in BitBlt>>#copyBits?
Best,
Christoph
________________________________ Von: Squeak-dev squeak-dev-bounces@lists.squeakfoundation.org im Auftrag von Tobias Pape Das.Linux@gmx.de Gesendet: Montag, 9. September 2019 14:56 Uhr An: The general-purpose Squeak developers list Betreff: Re: [squeak-dev] Bug in Form>>#asFormOfDepth:?
Hi Christoph,
On 09.09.2019, at 13:25, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi all,
consider the following example (print it):
"Example 1" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 2. g colorAt: 0 @ 0
Expected output: Color red. Actual output: Color black!
No, Forms of depth 1 are black and white, and of depth2 are gray.
Other examples:
"Example 2" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
yes, because you go from black/white to 32bit. I would have expected r0g0b0, but there might some rounding go on.
"Example 3" f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.973 g: 0.0 b: 0.0)"
Something's wonky here! If we do
(((Form extent: 1 asPoint depth: 16) colorAt: 0 @ 0 put: Color red) asFormOfDepth: 32) pixelValueAt: 0@0
we get 4294443008 (aka 0xFFF80000) which is a 32bit value. But the meaning is
11111111 11111000 00000000 00000000 ^ alpha ^ r ^ g ^ b
which means that the r component is not "upscaled" during the #asFormOfDepth: process o.O (see PS)
I am not familiar with color depths, but afaik Color red could be stored exactly using only 1 bit? Do I misunderstand the concept or is this really a bad output?
No, the first bit depth to support red is 4 bit.
Have a look at Color class>>colorFromPixelValue: p depth: d
BTW: You can use a ColorForm to work with your own palette, so that you can have for example a 1-bit form with 1=yellow & 0=red…
Best regards -Tobias
(I came across to this when performing #collectColors: on an 8 bit ColorForm loaded from disk, which did not work as expected.)
Best, Christoph
PS: PS: Color red is r:1.0 g:0.0 b:0.0 but stored in a different fashion:
Color comment: " Think of Color's instance variables as: r amount of red, a Float between 0.0 and 1.0. g amount of green, a Float between 0.0 and 1.0. b amount of blue, a Float between 0.0 and 1.0. (But, in fact, the three are encoded as values from 0 to 1023 and combined in a single integer, rgb. The user does not need to know this.) " that means "Color red" is stored as 0x3FF00000 or,
1111111111 0000000000 0000000000 ^ red ^ green ^ blue
that makes 10 bit per component.
However, in the 16 bit form we have only 5 bit per component, so,
f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. f pixelValueAt: 0@0.
yields 0x7C00 aka
11111 00000 00000 ^ r ^ g ^ b
On 09.09.2019, at 15:53, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi Tobias,
oops, I mistook the depth with the number of bits per channel. Sorry and many thanks for your explanations!
How would one fix the upscaling issue? Form>>#colormapIfNeededFor: returns nil in example 3, the comment in Color>>#colorMapIfNeededFrom:to: states this task is delegated to BitBlt. Is this comment wrong or is the defect in the primitive called that is in BitBlt>>#copyBits?
No, that part is only for cross-conversion of Forms and ColorForms -t
Best, Christoph
Von: Squeak-dev squeak-dev-bounces@lists.squeakfoundation.org im Auftrag von Tobias Pape Das.Linux@gmx.de Gesendet: Montag, 9. September 2019 14:56 Uhr An: The general-purpose Squeak developers list Betreff: Re: [squeak-dev] Bug in Form>>#asFormOfDepth:?
Hi Christoph,
On 09.09.2019, at 13:25, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi all,
consider the following example (print it):
"Example 1" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 2. g colorAt: 0 @ 0
Expected output: Color red. Actual output: Color black!
No, Forms of depth 1 are black and white, and of depth2 are gray.
Other examples:
"Example 2" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
yes, because you go from black/white to 32bit. I would have expected r0g0b0, but there might some rounding go on.
"Example 3" f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.973 g: 0.0 b: 0.0)"
Something's wonky here! If we do
(((Form extent: 1 asPoint depth: 16) colorAt: 0 @ 0 put: Color red) asFormOfDepth: 32) pixelValueAt: 0@0we get 4294443008 (aka 0xFFF80000) which is a 32bit value. But the meaning is
11111111 11111000 00000000 00000000 ^ alpha ^ r ^ g ^ bwhich means that the r component is not "upscaled" during the #asFormOfDepth: process o.O (see PS)
I am not familiar with color depths, but afaik Color red could be stored exactly using only 1 bit? Do I misunderstand the concept or is this really a bad output?
No, the first bit depth to support red is 4 bit.
Have a look at Color class>>colorFromPixelValue: p depth: d
BTW: You can use a ColorForm to work with your own palette, so that you can have for example a 1-bit form with 1=yellow & 0=red…
Best regards -Tobias
(I came across to this when performing #collectColors: on an 8 bit ColorForm loaded from disk, which did not work as expected.)
Best, Christoph
PS: PS: Color red is r:1.0 g:0.0 b:0.0 but stored in a different fashion:
Color comment: " Think of Color's instance variables as: r amount of red, a Float between 0.0 and 1.0. g amount of green, a Float between 0.0 and 1.0. b amount of blue, a Float between 0.0 and 1.0. (But, in fact, the three are encoded as values from 0 to 1023 and combined in a single integer, rgb. The user does not need to know this.) " that means "Color red" is stored as 0x3FF00000 or,
1111111111 0000000000 0000000000 ^ red ^ green ^ blue
that makes 10 bit per component.
However, in the 16 bit form we have only 5 bit per component, so,
f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. f pixelValueAt: 0@0.yields 0x7C00 aka
11111 00000 00000 ^ r ^ g ^ b
fwiw, Color r: 0.0 g: 0.0 b: 0.004is squeak's way of representing black in 16 bits so 0 can mean transparent
On 9/9/19 8:56 AM, Tobias Pape wrote:
Other examples:
"Example 2" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
yes, because you go from black/white to 32bit. I would have expected r0g0b0, but there might some rounding go on.
On 09.09.2019, at 17:03, Bob Arning arning315@comcast.net wrote:
fwiw, Color r: 0.0 g: 0.0 b: 0.004 is squeak's way of representing black in 16 bits so 0 can mean transparent
ah; i remember. thanks bob!
On 9/9/19 8:56 AM, Tobias Pape wrote:
Other examples:
"Example 2" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
yes, because you go from black/white to 32bit. I would have expected r0g0b0, but there might some rounding go on.
Any chance to fix this bug for 5.3?
The following would still be a functional workaround: [cid:fd67b6ba-ce69-44a3-94d8-362b808bcc7e]
( Reminder: The bug can be reproduced using "Example 3" f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 Expected: Color red Actual: (Color r: 0.973 g: 0.0 b: 0.0) )
Best, Christoph ________________________________ Von: Squeak-dev squeak-dev-bounces@lists.squeakfoundation.org im Auftrag von Tobias Pape Das.Linux@gmx.de Gesendet: Montag, 9. September 2019 16:56:03 An: The general-purpose Squeak developers list Betreff: Re: [squeak-dev] Bug in Form>>#asFormOfDepth:?
On 09.09.2019, at 15:53, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi Tobias,
oops, I mistook the depth with the number of bits per channel. Sorry and many thanks for your explanations!
How would one fix the upscaling issue? Form>>#colormapIfNeededFor: returns nil in example 3, the comment in Color>>#colorMapIfNeededFrom:to: states this task is delegated to BitBlt. Is this comment wrong or is the defect in the primitive called that is in BitBlt>>#copyBits?
No, that part is only for cross-conversion of Forms and ColorForms -t
Best, Christoph
Von: Squeak-dev squeak-dev-bounces@lists.squeakfoundation.org im Auftrag von Tobias Pape Das.Linux@gmx.de Gesendet: Montag, 9. September 2019 14:56 Uhr An: The general-purpose Squeak developers list Betreff: Re: [squeak-dev] Bug in Form>>#asFormOfDepth:?
Hi Christoph,
On 09.09.2019, at 13:25, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi all,
consider the following example (print it):
"Example 1" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 2. g colorAt: 0 @ 0
Expected output: Color red. Actual output: Color black!
No, Forms of depth 1 are black and white, and of depth2 are gray.
Other examples:
"Example 2" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
yes, because you go from black/white to 32bit. I would have expected r0g0b0, but there might some rounding go on.
"Example 3" f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.973 g: 0.0 b: 0.0)"
Something's wonky here! If we do
(((Form extent: 1 asPoint depth: 16) colorAt: 0 @ 0 put: Color red) asFormOfDepth: 32) pixelValueAt: 0@0we get 4294443008 (aka 0xFFF80000) which is a 32bit value. But the meaning is
11111111 11111000 00000000 00000000 ^ alpha ^ r ^ g ^ bwhich means that the r component is not "upscaled" during the #asFormOfDepth: process o.O (see PS)
I am not familiar with color depths, but afaik Color red could be stored exactly using only 1 bit? Do I misunderstand the concept or is this really a bad output?
No, the first bit depth to support red is 4 bit.
Have a look at Color class>>colorFromPixelValue: p depth: d
BTW: You can use a ColorForm to work with your own palette, so that you can have for example a 1-bit form with 1=yellow & 0=red…
Best regards -Tobias
(I came across to this when performing #collectColors: on an 8 bit ColorForm loaded from disk, which did not work as expected.)
Best, Christoph
PS: PS: Color red is r:1.0 g:0.0 b:0.0 but stored in a different fashion:
Color comment: " Think of Color's instance variables as: r amount of red, a Float between 0.0 and 1.0. g amount of green, a Float between 0.0 and 1.0. b amount of blue, a Float between 0.0 and 1.0. (But, in fact, the three are encoded as values from 0 to 1023 and combined in a single integer, rgb. The user does not need to know this.) " that means "Color red" is stored as 0x3FF00000 or,
1111111111 0000000000 0000000000 ^ red ^ green ^ blue
that makes 10 bit per component.
However, in the 16 bit form we have only 5 bit per component, so,
f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. f pixelValueAt: 0@0.yields 0x7C00 aka
11111 00000 00000 ^ r ^ g ^ b
Hi Christoph,
this looks performance critical. Take a look at BalloonEngine >> #bitBlt:. A color map is slower than computing the target value, according to Tim (tfel).
This issue is not that critical for the release, is it?
Btw, you can easily try out different display depth via the world menu:
Best, Marcel Am 15.12.2019 12:15:41 schrieb Thiede, Christoph christoph.thiede@student.hpi.uni-potsdam.de: Any chance to fix this bug for 5.3?
The following would still be a functional workaround:
( Reminder: The bug can be reproduced using "Example 3" f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 Expected: Color red Actual: (Color r: 0.973 g: 0.0 b: 0.0) )
Best, Christoph Von: Squeak-dev squeak-dev-bounces@lists.squeakfoundation.org im Auftrag von Tobias Pape Das.Linux@gmx.de Gesendet: Montag, 9. September 2019 16:56:03 An: The general-purpose Squeak developers list Betreff: Re: [squeak-dev] Bug in Form>>#asFormOfDepth:?
On 09.09.2019, at 15:53, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi Tobias,
oops, I mistook the depth with the number of bits per channel. Sorry and many thanks for your explanations!
How would one fix the upscaling issue? Form>>#colormapIfNeededFor: returns nil in example 3, the comment in Color>>#colorMapIfNeededFrom:to: states this task is delegated to BitBlt. Is this comment wrong or is the defect in the primitive called that is in BitBlt>>#copyBits?
No, that part is only for cross-conversion of Forms and ColorForms -t
Best, Christoph
Von: Squeak-dev squeak-dev-bounces@lists.squeakfoundation.org im Auftrag von Tobias Pape Das.Linux@gmx.de Gesendet: Montag, 9. September 2019 14:56 Uhr An: The general-purpose Squeak developers list Betreff: Re: [squeak-dev] Bug in Form>>#asFormOfDepth:? Hi Christoph,
On 09.09.2019, at 13:25, Thiede, Christoph Christoph.Thiede@student.hpi.uni-potsdam.de wrote:
Hi all,
consider the following example (print it):
"Example 1" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 2. g colorAt: 0 @ 0
Expected output: Color red. Actual output: Color black!
No, Forms of depth 1 are black and white, and of depth2 are gray.
Other examples:
"Example 2" f := Form extent: 1 asPoint depth: 1. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.0 g: 0.0 b: 0.004)"
yes, because you go from black/white to 32bit. I would have expected r0g0b0, but there might some rounding go on.
"Example 3" f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. g := f asFormOfDepth: 32. g colorAt: 0 @ 0 "--> (Color r: 0.973 g: 0.0 b: 0.0)"
Something's wonky here! If we do
(((Form extent: 1 asPoint depth: 16) colorAt: 0 @ 0 put: Color red) asFormOfDepth: 32) pixelValueAt: 0@0
we get 4294443008 (aka 0xFFF80000) which is a 32bit value. But the meaning is
11111111 11111000 00000000 00000000 ^ alpha ^ r ^ g ^ b
which means that the r component is not "upscaled" during the #asFormOfDepth: process o.O (see PS)
I am not familiar with color depths, but afaik Color red could be stored exactly using only 1 bit? Do I misunderstand the concept or is this really a bad output?
No, the first bit depth to support red is 4 bit.
Have a look at Color class>>colorFromPixelValue: p depth: d
BTW: You can use a ColorForm to work with your own palette, so that you can have for example a 1-bit form with 1=yellow & 0=red…
Best regards -Tobias
(I came across to this when performing #collectColors: on an 8 bit ColorForm loaded from disk, which did not work as expected.)
Best, Christoph
PS: PS: Color red is r:1.0 g:0.0 b:0.0 but stored in a different fashion:
Color comment: " Think of Color's instance variables as: r amount of red, a Float between 0.0 and 1.0. g amount of green, a Float between 0.0 and 1.0. b amount of blue, a Float between 0.0 and 1.0. (But, in fact, the three are encoded as values from 0 to 1023 and combined in a single integer, rgb. The user does not need to know this.) " that means "Color red" is stored as 0x3FF00000 or,
1111111111 0000000000 0000000000 ^ red ^ green ^ blue
that makes 10 bit per component.
However, in the 16 bit form we have only 5 bit per component, so,
f := Form extent: 1 asPoint depth: 16. f colorAt: 0 @ 0 put: Color red. f pixelValueAt: 0@0.
yields 0x7C00 aka
11111 00000 00000 ^ r ^ g ^ b
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