digitalmars.D.learn - Speed of horizontal flip
- tchaloupka (84/84) Apr 01 2015 Hi,
- bearophile (15/16) Apr 01 2015 If you have to perform performance benchmarks then use ldc or gdc.
- tchaloupka (20/24) Apr 01 2015 I tried it on my slower linux box (i5-2500K vs i7-2600K) without
- Dominikus Dittes Scherkl (5/12) Apr 02 2015 This very text should be placed somewhere prominent at the D
- John Colvin (46/46) Apr 01 2015 On Wednesday, 1 April 2015 at 13:52:06 UTC, tchaloupka wrote:
- tchaloupka (3/9) Apr 01 2015 Yes thats right, load, flip and save are all performed by GDI+ so
- thedeemon (2/2) Apr 01 2015 std.algorithm.reverse uses ranges, and shamefully DMD is really
- John Colvin (13/15) Apr 02 2015 The specialisation of reverse selected for slices does not use
- Rikki Cattermole (23/104) Apr 02 2015 Assuming I've done it correctly, Devisualization.Image takes around 8ms
- Rikki Cattermole (3/126) Apr 02 2015 My bad, forgot I decreased test image resolution to 256x256. I'm totally...
- John Colvin (17/168) Apr 02 2015 Have you considered just being able to grab an object with
- Rikki Cattermole (4/158) Apr 02 2015 I've got it down to ~ 12ms using dmd now. But if the image was much
- John Colvin (6/198) Apr 02 2015 That would be an insanely large image. If it was square it would
- Rikki Cattermole (6/177) Apr 02 2015 Most image editing software could definitely not handle it. I would be
- Vladimir Panteleev (3/16) Apr 05 2015 My implementation of flip takes 0ms ;)
Hi,
I have a bunch of square r16 and png images which I need to flip
horizontally.
My flip method looks like this:
void hFlip(T)(T[] data, int w)
{
import std.datetime : StopWatch;
StopWatch sw;
sw.start();
foreach(int i; 0..w)
{
auto row = data[i*w..(i+1)*w];
row.reverse();
}
sw.stop();
writeln("Img flipped in: ", sw.peek().msecs, "[ms]");
}
With simple r16 file format its pretty fast, but with RGB PNG
files (2048x2048) I noticed its somewhat slow so I tried to
PNG load - 90ms
PNG flip - 10ms
PNG save - 380ms
D using dlib (http://code.dlang.org/packages/dlib):
PNG load - 500ms
PNG flip - 30ms
PNG save - 950ms
D using imageformats
(http://code.dlang.org/packages/imageformats):
PNG load - 230ms
PNG flip - 30ms
PNG save - 1100ms
I used dmd-2.0.67 with -release -inline -O
debugging and even with that it is much faster.
I know that System.Drawing is using Windows GDI+, that can be
used with D too, but not on linux.
If we ignore the PNG loading and saving (didn't tried libpng
yet), even flip method itself is 3 times slower - I don't know D
enough to be sure if there isn't some more effecient way to make
the flip. I like how the slices can be used here.
possible from a system level programming language this can be
somewhat disappointing to see that pure D version is about 3
times slower.
Am I doing something utterly wrong?
Note that this example is not critical for me, it's just a simple
hobby script I use to move and flip some images - I can wait. But
I post it to see if this can be taken somewhat closer to what can
be expected from a system level programming language.
dlib:
auto im = loadPNG(name);
hFlip(cast(ubyte[3][])im.data, cast(int)im.width);
savePNG(im, newName);
imageformats:
auto im = read_image(name);
hFlip(cast(ubyte[3][])im.pixels, cast(int)im.w);
write_image(newName, im.w, im.h, im.pixels);
static void Main(string[] args)
{
var files = Directory.GetFiles(args[0]);
foreach (var f in files)
{
var sw = Stopwatch.StartNew();
var img = Image.FromFile(f);
Debug.WriteLine("Img loaded in {0}[ms]",
(int)sw.Elapsed.TotalMilliseconds);
sw.Restart();
img.RotateFlip(RotateFlipType.RotateNoneFlipX);
Debug.WriteLine("Img flipped in {0}[ms]",
(int)sw.Elapsed.TotalMilliseconds);
sw.Restart();
img.Save(Path.Combine(args[0], "test_" +
Path.GetFileName(f)));
Debug.WriteLine("Img saved in {0}[ms]",
(int)sw.Elapsed.TotalMilliseconds);
sw.Stop();
}
}
Apr 01 2015
tchaloupka:Am I doing something utterly wrong?If you have to perform performance benchmarks then use ldc or gdc. Also disable bound tests with your compilation switches. Sometimes reverse() is not efficient, I think, it should be improved. Try to replace it with a little function written by you. Add the usual pure/nothrow/ nogc/ safe annotations where you can (they don't increase speed much, usually). And you refer to flip as "method", so if you are using classes don't forget to make the method final. Profile the code and look for the performance bottlenecks. You can even replace the *w multiplications with an increment of an index each loop, but this time saving is dwarfed by the reverse(). Bye, bearophile
Apr 01 2015
"tchaloupka" <chalucha gmail.com> On Wednesday, 1 April 2015 at 14:00:52 UTC, bearophile wrote:tchaloupka:I tried it on my slower linux box (i5-2500K vs i7-2600K) without change with these results: Img loaded in 108[ms] Img flipped in 22[ms] Img saved in 492[ms] dmd-2.067: Png loaded in: 150[ms] Img flipped in: 28[ms] Png saved in: 765[ms] gdc-4.8.3: Png loaded in: 121[ms] Img flipped in: 4[ms] Png saved in: 686[ms] ldc2-0_15: Png loaded in: 106[ms] Img flipped in: 4[ms] Png saved in: 610[ms] I'm ok with that, thx.Am I doing something utterly wrong?If you have to perform performance benchmarks then use ldc or gdc.
Apr 01 2015
On Wednesday, 1 April 2015 at 14:00:52 UTC, bearophile wrote:If you have to perform performance benchmarks then use ldc or gdc. Also disable bound tests with your compilation switches. Add the usual pure/nothrow/ nogc/ safe annotations where you can (they don't increase speed much, usually). if you are using classes don't forget to make the method final. Profile the code and look for the performance bottlenecks.This very text should be placed somewhere prominent at the D homepage if we don't want to constantly dissapoint people who come with the impession that D should be at the same speed level as C/C++ but their test programs aren't.
Apr 02 2015
On Wednesday, 1 April 2015 at 13:52:06 UTC, tchaloupka wrote:
<snip>
I'm pretty sure that the flipping happens in GDI+ as well. You
the work is C and/or C++, quite possibly carefully optimised over
many years by microsoft.
could easily just set the iteration scheme and return (like
numpy.ndarray.T does, if you're familiar with python).
dmd does not produce particularly fast code. ldc and gdc are much
better at that.
Sadly, std.algorithm.reserve isn't perhaps as fast as it could be
for arrays of static arrays, at least in theory. Try this, but I
hope that with a properly optimised build from ldc/gdc it won't
make any difference:
void reverse(ubyte[3][] r)
{
immutable last = r.length-1;
immutable steps = r.length/2;
foreach(immutable i; 0 .. steps)
{
immutable tmp = r[i];
r[i] = r[last - i];
r[last - i] = tmp;
}
}
unittest
{
ubyte[3] a = [1,2,3];
ubyte[3] b = [7,6,5];
auto c = [a,b];
c.reverse();
assert(c == [b,a]);
ubyte[3] d = [9,4,6];
auto e = [a,b,d];
e.reverse();
assert(e == [d,b,a]);
auto f = e.dup;
e.reverse;
e.reverse;
assert(f == e);
}
Apr 01 2015
On Wednesday, 1 April 2015 at 16:08:14 UTC, John Colvin wrote:On Wednesday, 1 April 2015 at 13:52:06 UTC, tchaloupka wrote: <snip> I'm pretty sure that the flipping happens in GDI+ as well. You the work is C and/or C++, quite possibly carefully optimised over many years by microsoft.Yes thats right, load, flip and save are all performed by GDI+ so
Apr 01 2015
std.algorithm.reverse uses ranges, and shamefully DMD is really bad at optimizing away range-induced costs.
Apr 01 2015
On Thursday, 2 April 2015 at 05:21:08 UTC, thedeemon wrote:std.algorithm.reverse uses ranges, and shamefully DMD is really bad at optimizing away range-induced costs.The specialisation of reverse selected for slices does not use the range interface, it's all just indexing. The only overheads come from: a) function calls, if the inliner isn't doing its job (which it really should be in these cases). b) a check for aliasing in swapAt, which is only done for ranges of static arrays. Again, should be optimised away in this case, but it's possible DMD doesn't manage it. Either way, it's a trivially predictable branch and should be effectively free at the CPU level. Once you've got past those, it's just straight loop I posted before.
Apr 02 2015
On 2/04/2015 2:52 a.m., tchaloupka wrote:
Hi,
I have a bunch of square r16 and png images which I need to flip
horizontally.
My flip method looks like this:
void hFlip(T)(T[] data, int w)
{
import std.datetime : StopWatch;
StopWatch sw;
sw.start();
foreach(int i; 0..w)
{
auto row = data[i*w..(i+1)*w];
row.reverse();
}
sw.stop();
writeln("Img flipped in: ", sw.peek().msecs, "[ms]");
}
With simple r16 file format its pretty fast, but with RGB PNG
files (2048x2048) I noticed its somewhat slow so I tried to
PNG load - 90ms
PNG flip - 10ms
PNG save - 380ms
D using dlib (http://code.dlang.org/packages/dlib):
PNG load - 500ms
PNG flip - 30ms
PNG save - 950ms
D using imageformats
(http://code.dlang.org/packages/imageformats):
PNG load - 230ms
PNG flip - 30ms
PNG save - 1100ms
I used dmd-2.0.67 with -release -inline -O
debugging and even with that it is much faster.
I know that System.Drawing is using Windows GDI+, that can be
used with D too, but not on linux.
If we ignore the PNG loading and saving (didn't tried libpng
yet), even flip method itself is 3 times slower - I don't know D
enough to be sure if there isn't some more effecient way to make
the flip. I like how the slices can be used here.
possible from a system level programming language this can be
somewhat disappointing to see that pure D version is about 3
times slower.
Am I doing something utterly wrong?
Note that this example is not critical for me, it's just a simple
hobby script I use to move and flip some images - I can wait. But
I post it to see if this can be taken somewhat closer to what can
be expected from a system level programming language.
dlib:
auto im = loadPNG(name);
hFlip(cast(ubyte[3][])im.data, cast(int)im.width);
savePNG(im, newName);
imageformats:
auto im = read_image(name);
hFlip(cast(ubyte[3][])im.pixels, cast(int)im.w);
write_image(newName, im.w, im.h, im.pixels);
static void Main(string[] args)
{
var files = Directory.GetFiles(args[0]);
foreach (var f in files)
{
var sw = Stopwatch.StartNew();
var img = Image.FromFile(f);
Debug.WriteLine("Img loaded in {0}[ms]",
(int)sw.Elapsed.TotalMilliseconds);
sw.Restart();
img.RotateFlip(RotateFlipType.RotateNoneFlipX);
Debug.WriteLine("Img flipped in {0}[ms]",
(int)sw.Elapsed.TotalMilliseconds);
sw.Restart();
img.Save(Path.Combine(args[0], "test_" +
Path.GetFileName(f)));
Debug.WriteLine("Img saved in {0}[ms]",
(int)sw.Elapsed.TotalMilliseconds);
sw.Stop();
}
}
Assuming I've done it correctly, Devisualization.Image takes around 8ms
in debug mode to flip horizontally using dmd. But 3ms for release.
module test;
void main() {
import devisualization.image;
import devisualization.image.mutable;
import devisualization.util.core.linegraph;
import std.stdio;
writeln("===============\nREAD\n===============");
Image img = imageFromFile("test/large.png");
img = new MutableImage(img);
import std.datetime : StopWatch;
StopWatch sw;
sw.start();
foreach(i; 0 .. 1000) {
img.flipHorizontal;
}
sw.stop();
writeln("Img flipped in: ", sw.peek().msecs / 1000, "[ms]");
}
I was planning on doing this earlier. But I discovered a PR I pulled
which fixed for 2.067 broke chunk types reading.
Apr 02 2015
On 2/04/2015 10:47 p.m., Rikki Cattermole wrote:On 2/04/2015 2:52 a.m., tchaloupka wrote:My bad, forgot I decreased test image resolution to 256x256. I'm totally out of the running. I have some serious work to do by the looks.Hi, I have a bunch of square r16 and png images which I need to flip horizontally. My flip method looks like this: void hFlip(T)(T[] data, int w) { import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(int i; 0..w) { auto row = data[i*w..(i+1)*w]; row.reverse(); } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs, "[ms]"); } With simple r16 file format its pretty fast, but with RGB PNG files (2048x2048) I noticed its somewhat slow so I tried to PNG load - 90ms PNG flip - 10ms PNG save - 380ms D using dlib (http://code.dlang.org/packages/dlib): PNG load - 500ms PNG flip - 30ms PNG save - 950ms D using imageformats (http://code.dlang.org/packages/imageformats): PNG load - 230ms PNG flip - 30ms PNG save - 1100ms I used dmd-2.0.67 with -release -inline -O debugging and even with that it is much faster. I know that System.Drawing is using Windows GDI+, that can be used with D too, but not on linux. If we ignore the PNG loading and saving (didn't tried libpng yet), even flip method itself is 3 times slower - I don't know D enough to be sure if there isn't some more effecient way to make the flip. I like how the slices can be used here. possible from a system level programming language this can be somewhat disappointing to see that pure D version is about 3 times slower. Am I doing something utterly wrong? Note that this example is not critical for me, it's just a simple hobby script I use to move and flip some images - I can wait. But I post it to see if this can be taken somewhat closer to what can be expected from a system level programming language. dlib: auto im = loadPNG(name); hFlip(cast(ubyte[3][])im.data, cast(int)im.width); savePNG(im, newName); imageformats: auto im = read_image(name); hFlip(cast(ubyte[3][])im.pixels, cast(int)im.w); write_image(newName, im.w, im.h, im.pixels); static void Main(string[] args) { var files = Directory.GetFiles(args[0]); foreach (var f in files) { var sw = Stopwatch.StartNew(); var img = Image.FromFile(f); Debug.WriteLine("Img loaded in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.RotateFlip(RotateFlipType.RotateNoneFlipX); Debug.WriteLine("Img flipped in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.Save(Path.Combine(args[0], "test_" + Path.GetFileName(f))); Debug.WriteLine("Img saved in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Stop(); } }Assuming I've done it correctly, Devisualization.Image takes around 8ms in debug mode to flip horizontally using dmd. But 3ms for release. module test; void main() { import devisualization.image; import devisualization.image.mutable; import devisualization.util.core.linegraph; import std.stdio; writeln("===============\nREAD\n==============="); Image img = imageFromFile("test/large.png"); img = new MutableImage(img); import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(i; 0 .. 1000) { img.flipHorizontal; } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs / 1000, "[ms]"); } I was planning on doing this earlier. But I discovered a PR I pulled which fixed for 2.067 broke chunk types reading.
Apr 02 2015
On Thursday, 2 April 2015 at 09:55:15 UTC, Rikki Cattermole wrote:On 2/04/2015 10:47 p.m., Rikki Cattermole wrote:Have you considered just being able to grab an object with changed iteration order instead of actually doing the flip? The same goes for transposes and 90º rotations. Sure, sometimes you do need actually rearrange the memory and in a subset of those cases you need it to be done fast, but a lot of the time you're better off* just using a different iteration scheme (which, for ranges, should probably be part of the type to avoid checking the scheme every iteration). *for speed and memory reasons. Need to keep the original and the transpose? No need to for any duplicates Note that this is what numpy does with transposes. The .T and .transpose methods of ndarray don't actually modify the data, they just set the memory order** whereas the transpose function actually moves memory around. **using a runtime flag, which is ok for them because internal iteration lets you only branch once on it.On 2/04/2015 2:52 a.m., tchaloupka wrote:My bad, forgot I decreased test image resolution to 256x256. I'm totally out of the running. I have some serious work to do by the looks.Hi, I have a bunch of square r16 and png images which I need to flip horizontally. My flip method looks like this: void hFlip(T)(T[] data, int w) { import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(int i; 0..w) { auto row = data[i*w..(i+1)*w]; row.reverse(); } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs, "[ms]"); } With simple r16 file format its pretty fast, but with RGB PNG files (2048x2048) I noticed its somewhat slow so I tried to PNG load - 90ms PNG flip - 10ms PNG save - 380ms D using dlib (http://code.dlang.org/packages/dlib): PNG load - 500ms PNG flip - 30ms PNG save - 950ms D using imageformats (http://code.dlang.org/packages/imageformats): PNG load - 230ms PNG flip - 30ms PNG save - 1100ms I used dmd-2.0.67 with -release -inline -O for debugging and even with that it is much faster. I know that System.Drawing is using Windows GDI+, that can be used with D too, but not on linux. If we ignore the PNG loading and saving (didn't tried libpng yet), even flip method itself is 3 times slower - I don't know D enough to be sure if there isn't some more effecient way to make the flip. I like how the slices can be used here. possible from a system level programming language this can be somewhat disappointing to see that pure D version is about 3 times slower. Am I doing something utterly wrong? Note that this example is not critical for me, it's just a simple hobby script I use to move and flip some images - I can wait. But I post it to see if this can be taken somewhat closer to what can be expected from a system level programming language. dlib: auto im = loadPNG(name); hFlip(cast(ubyte[3][])im.data, cast(int)im.width); savePNG(im, newName); imageformats: auto im = read_image(name); hFlip(cast(ubyte[3][])im.pixels, cast(int)im.w); write_image(newName, im.w, im.h, im.pixels); static void Main(string[] args) { var files = Directory.GetFiles(args[0]); foreach (var f in files) { var sw = Stopwatch.StartNew(); var img = Image.FromFile(f); Debug.WriteLine("Img loaded in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.RotateFlip(RotateFlipType.RotateNoneFlipX); Debug.WriteLine("Img flipped in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.Save(Path.Combine(args[0], "test_" + Path.GetFileName(f))); Debug.WriteLine("Img saved in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Stop(); } }Assuming I've done it correctly, Devisualization.Image takes around 8ms in debug mode to flip horizontally using dmd. But 3ms for release. module test; void main() { import devisualization.image; import devisualization.image.mutable; import devisualization.util.core.linegraph; import std.stdio; writeln("===============\nREAD\n==============="); Image img = imageFromFile("test/large.png"); img = new MutableImage(img); import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(i; 0 .. 1000) { img.flipHorizontal; } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs / 1000, "[ms]"); } I was planning on doing this earlier. But I discovered a PR I pulled which fixed for 2.067 broke chunk types reading.
Apr 02 2015
On 3/04/2015 12:29 a.m., John Colvin wrote:On Thursday, 2 April 2015 at 09:55:15 UTC, Rikki Cattermole wrote:I've got it down to ~ 12ms using dmd now. But if the image was much bigger (lets say a height of ushort.max). I wouldn't be able to use a little trick. But this is only because I'm using multithreading.On 2/04/2015 10:47 p.m., Rikki Cattermole wrote:Have you considered just being able to grab an object with changed iteration order instead of actually doing the flip? The same goes for transposes and 90º rotations. Sure, sometimes you do need actually rearrange the memory and in a subset of those cases you need it to be done fast, but a lot of the time you're better off* just using a different iteration scheme (which, for ranges, should probably be part of the type to avoid checking the scheme every iteration). *for speed and memory reasons. Need to keep the original and the transpose? No need to for any duplicates Note that this is what numpy does with transposes. The .T and .transpose methods of ndarray don't actually modify the data, they just set the memory order** whereas the transpose function actually moves memory around. **using a runtime flag, which is ok for them because internal iteration lets you only branch once on it.On 2/04/2015 2:52 a.m., tchaloupka wrote:My bad, forgot I decreased test image resolution to 256x256. I'm totally out of the running. I have some serious work to do by the looks.Hi, I have a bunch of square r16 and png images which I need to flip horizontally. My flip method looks like this: void hFlip(T)(T[] data, int w) { import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(int i; 0..w) { auto row = data[i*w..(i+1)*w]; row.reverse(); } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs, "[ms]"); } With simple r16 file format its pretty fast, but with RGB PNG files (2048x2048) I noticed its somewhat slow so I tried to PNG load - 90ms PNG flip - 10ms PNG save - 380ms D using dlib (http://code.dlang.org/packages/dlib): PNG load - 500ms PNG flip - 30ms PNG save - 950ms D using imageformats (http://code.dlang.org/packages/imageformats): PNG load - 230ms PNG flip - 30ms PNG save - 1100ms I used dmd-2.0.67 with -release -inline -O debugging and even with that it is much faster. I know that System.Drawing is using Windows GDI+, that can be used with D too, but not on linux. If we ignore the PNG loading and saving (didn't tried libpng yet), even flip method itself is 3 times slower - I don't know D enough to be sure if there isn't some more effecient way to make the flip. I like how the slices can be used here. possible from a system level programming language this can be somewhat disappointing to see that pure D version is about 3 times slower. Am I doing something utterly wrong? Note that this example is not critical for me, it's just a simple hobby script I use to move and flip some images - I can wait. But I post it to see if this can be taken somewhat closer to what can be expected from a system level programming language. dlib: auto im = loadPNG(name); hFlip(cast(ubyte[3][])im.data, cast(int)im.width); savePNG(im, newName); imageformats: auto im = read_image(name); hFlip(cast(ubyte[3][])im.pixels, cast(int)im.w); write_image(newName, im.w, im.h, im.pixels); static void Main(string[] args) { var files = Directory.GetFiles(args[0]); foreach (var f in files) { var sw = Stopwatch.StartNew(); var img = Image.FromFile(f); Debug.WriteLine("Img loaded in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.RotateFlip(RotateFlipType.RotateNoneFlipX); Debug.WriteLine("Img flipped in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.Save(Path.Combine(args[0], "test_" + Path.GetFileName(f))); Debug.WriteLine("Img saved in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Stop(); } }Assuming I've done it correctly, Devisualization.Image takes around 8ms in debug mode to flip horizontally using dmd. But 3ms for release. module test; void main() { import devisualization.image; import devisualization.image.mutable; import devisualization.util.core.linegraph; import std.stdio; writeln("===============\nREAD\n==============="); Image img = imageFromFile("test/large.png"); img = new MutableImage(img); import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(i; 0 .. 1000) { img.flipHorizontal; } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs / 1000, "[ms]"); } I was planning on doing this earlier. But I discovered a PR I pulled which fixed for 2.067 broke chunk types reading.
Apr 02 2015
On Thursday, 2 April 2015 at 11:49:44 UTC, Rikki Cattermole wrote:On 3/04/2015 12:29 a.m., John Colvin wrote:That would be an insanely large image. If it was square it would be a 4GiB image. I think it's safe to say that someone with images that large will be looking for quite specialised solutions and wouldn't be disappointed if things aren't optimally fast off-the-shelf!On Thursday, 2 April 2015 at 09:55:15 UTC, Rikki Cattermole wrote:I've got it down to ~ 12ms using dmd now. But if the image was much bigger (lets say a height of ushort.max). I wouldn't be able to use a little trick. But this is only because I'm using multithreading.On 2/04/2015 10:47 p.m., Rikki Cattermole wrote:Have you considered just being able to grab an object with changed iteration order instead of actually doing the flip? The same goes for transposes and 90º rotations. Sure, sometimes you do need actually rearrange the memory and in a subset of those cases you need it to be done fast, but a lot of the time you're better off* just using a different iteration scheme (which, for ranges, should probably be part of the type to avoid checking the scheme every iteration). *for speed and memory reasons. Need to keep the original and the transpose? No need to for any duplicates Note that this is what numpy does with transposes. The .T and .transpose methods of ndarray don't actually modify the data, they just set the memory order** whereas the transpose function actually moves memory around. **using a runtime flag, which is ok for them because internal iteration lets you only branch once on it.On 2/04/2015 2:52 a.m., tchaloupka wrote:My bad, forgot I decreased test image resolution to 256x256. I'm totally out of the running. I have some serious work to do by the looks.Hi, I have a bunch of square r16 and png images which I need to flip horizontally. My flip method looks like this: void hFlip(T)(T[] data, int w) { import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(int i; 0..w) { auto row = data[i*w..(i+1)*w]; row.reverse(); } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs, "[ms]"); } With simple r16 file format its pretty fast, but with RGB PNG files (2048x2048) I noticed its somewhat slow so I tried to PNG load - 90ms PNG flip - 10ms PNG save - 380ms D using dlib (http://code.dlang.org/packages/dlib): PNG load - 500ms PNG flip - 30ms PNG save - 950ms D using imageformats (http://code.dlang.org/packages/imageformats): PNG load - 230ms PNG flip - 30ms PNG save - 1100ms I used dmd-2.0.67 with -release -inline -O for debugging and even with that it is much faster. I know that System.Drawing is using Windows GDI+, that can be used with D too, but not on linux. If we ignore the PNG loading and saving (didn't tried libpng yet), even flip method itself is 3 times slower - I don't know D enough to be sure if there isn't some more effecient way to make the flip. I like how the slices can be used here. as possible from a system level programming language this can be somewhat disappointing to see that pure D version is about 3 times slower. Am I doing something utterly wrong? Note that this example is not critical for me, it's just a simple hobby script I use to move and flip some images - I can wait. But I post it to see if this can be taken somewhat closer to what can be expected from a system level programming language. dlib: auto im = loadPNG(name); hFlip(cast(ubyte[3][])im.data, cast(int)im.width); savePNG(im, newName); imageformats: auto im = read_image(name); hFlip(cast(ubyte[3][])im.pixels, cast(int)im.w); write_image(newName, im.w, im.h, im.pixels); static void Main(string[] args) { var files = Directory.GetFiles(args[0]); foreach (var f in files) { var sw = Stopwatch.StartNew(); var img = Image.FromFile(f); Debug.WriteLine("Img loaded in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.RotateFlip(RotateFlipType.RotateNoneFlipX); Debug.WriteLine("Img flipped in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.Save(Path.Combine(args[0], "test_" + Path.GetFileName(f))); Debug.WriteLine("Img saved in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Stop(); } }Assuming I've done it correctly, Devisualization.Image takes around 8ms in debug mode to flip horizontally using dmd. But 3ms for release. module test; void main() { import devisualization.image; import devisualization.image.mutable; import devisualization.util.core.linegraph; import std.stdio; writeln("===============\nREAD\n==============="); Image img = imageFromFile("test/large.png"); img = new MutableImage(img); import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(i; 0 .. 1000) { img.flipHorizontal; } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs / 1000, "[ms]"); } I was planning on doing this earlier. But I discovered a PR I pulled which fixed for 2.067 broke chunk types reading.
Apr 02 2015
On 3/04/2015 4:27 a.m., John Colvin wrote:On Thursday, 2 April 2015 at 11:49:44 UTC, Rikki Cattermole wrote:Most image editing software could definitely not handle it. I would be very surprised if e.g. libpng can even read such a file. Although I'm pretty sure mine can ;) Worse case scenario for more than ushort.max I think it'll be a couple hundred ms.On 3/04/2015 12:29 a.m., John Colvin wrote:That would be an insanely large image. If it was square it would be a 4GiB image. I think it's safe to say that someone with images that large will be looking for quite specialised solutions and wouldn't be disappointed if things aren't optimally fast off-the-shelf!On Thursday, 2 April 2015 at 09:55:15 UTC, Rikki Cattermole wrote:I've got it down to ~ 12ms using dmd now. But if the image was much bigger (lets say a height of ushort.max). I wouldn't be able to use a little trick. But this is only because I'm using multithreading.On 2/04/2015 10:47 p.m., Rikki Cattermole wrote:Have you considered just being able to grab an object with changed iteration order instead of actually doing the flip? The same goes for transposes and 90º rotations. Sure, sometimes you do need actually rearrange the memory and in a subset of those cases you need it to be done fast, but a lot of the time you're better off* just using a different iteration scheme (which, for ranges, should probably be part of the type to avoid checking the scheme every iteration). *for speed and memory reasons. Need to keep the original and the transpose? No need to for any duplicates Note that this is what numpy does with transposes. The .T and .transpose methods of ndarray don't actually modify the data, they just set the memory order** whereas the transpose function actually moves memory around. **using a runtime flag, which is ok for them because internal iteration lets you only branch once on it.On 2/04/2015 2:52 a.m., tchaloupka wrote:My bad, forgot I decreased test image resolution to 256x256. I'm totally out of the running. I have some serious work to do by the looks.Hi, I have a bunch of square r16 and png images which I need to flip horizontally. My flip method looks like this: void hFlip(T)(T[] data, int w) { import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(int i; 0..w) { auto row = data[i*w..(i+1)*w]; row.reverse(); } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs, "[ms]"); } With simple r16 file format its pretty fast, but with RGB PNG files (2048x2048) I noticed its somewhat slow so I tried to PNG load - 90ms PNG flip - 10ms PNG save - 380ms D using dlib (http://code.dlang.org/packages/dlib): PNG load - 500ms PNG flip - 30ms PNG save - 950ms D using imageformats (http://code.dlang.org/packages/imageformats): PNG load - 230ms PNG flip - 30ms PNG save - 1100ms I used dmd-2.0.67 with -release -inline -O debugging and even with that it is much faster. I know that System.Drawing is using Windows GDI+, that can be used with D too, but not on linux. If we ignore the PNG loading and saving (didn't tried libpng yet), even flip method itself is 3 times slower - I don't know D enough to be sure if there isn't some more effecient way to make the flip. I like how the slices can be used here. possible from a system level programming language this can be somewhat disappointing to see that pure D version is about 3 times slower. Am I doing something utterly wrong? Note that this example is not critical for me, it's just a simple hobby script I use to move and flip some images - I can wait. But I post it to see if this can be taken somewhat closer to what can be expected from a system level programming language. dlib: auto im = loadPNG(name); hFlip(cast(ubyte[3][])im.data, cast(int)im.width); savePNG(im, newName); imageformats: auto im = read_image(name); hFlip(cast(ubyte[3][])im.pixels, cast(int)im.w); write_image(newName, im.w, im.h, im.pixels); static void Main(string[] args) { var files = Directory.GetFiles(args[0]); foreach (var f in files) { var sw = Stopwatch.StartNew(); var img = Image.FromFile(f); Debug.WriteLine("Img loaded in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.RotateFlip(RotateFlipType.RotateNoneFlipX); Debug.WriteLine("Img flipped in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Restart(); img.Save(Path.Combine(args[0], "test_" + Path.GetFileName(f))); Debug.WriteLine("Img saved in {0}[ms]", (int)sw.Elapsed.TotalMilliseconds); sw.Stop(); } }Assuming I've done it correctly, Devisualization.Image takes around 8ms in debug mode to flip horizontally using dmd. But 3ms for release. module test; void main() { import devisualization.image; import devisualization.image.mutable; import devisualization.util.core.linegraph; import std.stdio; writeln("===============\nREAD\n==============="); Image img = imageFromFile("test/large.png"); img = new MutableImage(img); import std.datetime : StopWatch; StopWatch sw; sw.start(); foreach(i; 0 .. 1000) { img.flipHorizontal; } sw.stop(); writeln("Img flipped in: ", sw.peek().msecs / 1000, "[ms]"); } I was planning on doing this earlier. But I discovered a PR I pulled which fixed for 2.067 broke chunk types reading.
Apr 02 2015
On Wednesday, 1 April 2015 at 13:52:06 UTC, tchaloupka wrote:PNG load - 90ms PNG flip - 10ms PNG save - 380ms D using dlib (http://code.dlang.org/packages/dlib): PNG load - 500ms PNG flip - 30ms PNG save - 950ms D using imageformats (http://code.dlang.org/packages/imageformats): PNG load - 230ms PNG flip - 30ms PNG save - 1100msMy implementation of flip takes 0ms ;) http://blog.thecybershadow.net/2014/03/21/functional-image-processing-in-d/
Apr 05 2015