Re: JPG and PNG decoder
it's not that hard to write a baseline jpeg encoder. it's not harder than decoding. there are many tutorials and examples online. Am 17.06.2012, 09:55 Uhr, schrieb cal : On Sunday, 17 June 2012 at 07:07:35 UTC, Philippe Sigaud wrote: Still, I'm interested in writing a JPEG/PNG to disk from a ubyte[3][][], or whatever. Do you mean that you want to encode a ubyte array to disk as JPEG/PNG? Encoding a JPEG would be a bit of work I think, the format's kind of a monster. PNG should be easier, depending on how good you want the compression to be. If you don't care too much about compression level, you simply zlib compress the data, write it out by image row/scanline, include appropriate header and chunk info, and you're done. I'll give a simple encoder a go if you think you could use it. Cheers, cal -- Erstellt mit Operas revolutionärem E-Mail-Modul: http://www.opera.com/mail/
Re: JPG and PNG decoder
On Thursday, 21 June 2012 at 17:58:47 UTC, Stewart Gordon wrote:
On 18/06/2012 00:49, cal wrote:
ubyte[] data = some data;
Image img = new Img!(Px.R8G8B8)(width, height, data);
Image? Img?
img.write("mypng.png");
Image is the interface, Img the templated class that does all the
work. It is parameterized by the pixel format. It may not be the
best strategy (or naming scheme!) but enumerating the formats and
templating based on that limited the number of cases I had to
think about.
Does it always take in a ubyte[], or does that depend on the
bit depth?
It currently just takes a ubyte, and doesn't do any rearranging
of the array, so it will only work for 8-bit depths. If you had
4-bit greyscale tightly packed into your ubyte (two pixels per
byte) then it would not be correctly interpreted, nor would 16
bit. The reason was I didn't want to have the Image class 'own'
the passed-in array. If it did own it, then it would be free to
unpack the smaller bit depths the way it does when decoding. I
will fix this when I have time to think about it a bit more.
Re: JPG and PNG decoder
On 18/06/2012 00:49, cal wrote:
ubyte[] data = some data;
Image img = new Img!(Px.R8G8B8)(width, height, data);
Image? Img?
img.write("mypng.png");
It uses adaptive filtering, and should work with the pixel formats supported by
the image
class (except for the 16 bit ones I've just realised). I've only tested it on
images that
I have previously loaded in however.
Does it always take in a ubyte[], or does that depend on the bit depth?
Stewart, I used your makepng.d as a template for this, can I add you to the
author list?
By all means.
I look forward to seeing what you've come up with.
Stewart.
Re: JPG and PNG decoder
On Sunday, 17 June 2012 at 20:10:28 UTC, cal wrote: though I have worlds of trouble with const-ness, I will endeavour to add those guarantees :) What I usually do, unless it's just an obvious case, is write code without concern for const-ness, then write a thorough test and step through one function/whatever at a time and apply const/inout/pure/nothrow/etc, do any apparent refactoring, and check the test. Writing the test helps me grok as many imaginable cases as possible, and doing it incrementally avoids massive "error cascades" from the compiler.
Re: JPG and PNG decoder
On Sunday, 17 June 2012 at 23:17:54 UTC, Stewart Gordon wrote:
You two should fuse it into one module, to give us
loading/writing.
That would be quite cool.
I don't know how much of the code will need rewriting in order
to support interlacing or all PNG colour types/depths.
But I also began writing a PNG library a while back - with the
intention that it will be a full PNG editing library, not just
encoding/decoding of the image data. But I haven't had much
time to work on it recently. And it would help a lot if we
could have the replacement for std.stream some time soon.
Stewart.
I just pushed an update which implements a PNG encoder. It is
implemented in the Image class as a write method. If you have a
raw buffer, and want to encode it, you can do something like this:
ubyte[] data = some data;
Image img = new Img!(Px.R8G8B8)(width, height, data);
img.write("mypng.png");
It uses adaptive filtering, and should work with the pixel
formats supported by the image class (except for the 16 bit ones
I've just realised). I've only tested it on images that I have
previously loaded in however.
Stewart, I used your makepng.d as a template for this, can I add
you to the author list?
Also, if preferred, I can keep the master branch as a single
merged module, just let me know.
Cheers,
cal
Re: JPG and PNG decoder
On 17/06/2012 14:38, Philippe Sigaud wrote: On Sun, Jun 17, 2012 at 3:25 PM, Stewart Gordon wrote: FWIW a while ago I wrote a simple experimental program that generates an image and encodes it as a PNG. And I've just tweaked it and updated it to D2 (attached). It supports only truecolour with 8 bits per sample, but it supports filtering, though it isn't adaptive (you just specify the filter to use when you run the program). Nice one, works OK here! (DMD 2.059, Linux 32bits) (DMD -property asks for '@property' after IHDR bigEndian()) Good catch. It's probably time we deprecated using property syntax on non-properties. You two should fuse it into one module, to give us loading/writing. That would be quite cool. I don't know how much of the code will need rewriting in order to support interlacing or all PNG colour types/depths. But I also began writing a PNG library a while back - with the intention that it will be a full PNG editing library, not just encoding/decoding of the image data. But I haven't had much time to work on it recently. And it would help a lot if we could have the replacement for std.stream some time soon. Stewart.
Re: JPG and PNG decoder
On Sunday, 17 June 2012 at 12:35:41 UTC, David wrote: Cool so I don't need to use my stb_image binding ( https://bitbucket.org/dav1d/gl-utils/src/0b97f77c14d7/stb_image ) anylonger! I used stb_image with C++ opengl projects, and it was great. stb_truetype is another gem, I would love to write a truetype loader, but I think the payoff is not worth the effort given the freetype bindings.
Re: JPG and PNG decoder
On Sunday, 17 June 2012 at 12:15:36 UTC, bearophile wrote: Suggestions on the code: - Try to use final switches. - switch cases don't need (), so instead of case(foo): write case foo: - Try to add const/immutable/pure/nothrow where possible. Bye, bearophile Problem with final switches in this context is that images may be corrupt or badly encoded or something, which the decoder should just handle gracefully through a default I think, without crashing. The case statements though I will change, and though I have worlds of trouble with const-ness, I will endeavour to add those guarantees :) Thanks for looking through
Re: JPG and PNG decoder
I have a simple png writer too if that's of use to you https://github.com/adamdruppe/misc-stuff-including-D-programming-language-web-stuff image.d and png.d. Somewhat suboptimal to use, since I ported some of my old C code almost directly to it, and it still works like C.
Re: JPG and PNG decoder
On Sun, Jun 17, 2012 at 3:25 PM, Stewart Gordon wrote: > > FWIW a while ago I wrote a simple experimental program that generates an > image and encodes it as a PNG. And I've just tweaked it and updated it to > D2 (attached). It supports only truecolour with 8 bits per sample, but it > supports filtering, though it isn't adaptive (you just specify the filter to > use when you run the program). Nice one, works OK here! (DMD 2.059, Linux 32bits) (DMD -property asks for '@property' after IHDR bigEndian()) You two should fuse it into one module, to give us loading/writing. That would be quite cool.
Re: JPG and PNG decoder
On 17/06/2012 08:55, cal wrote:
If you don't care too much about compression level, you simply zlib
compress the data, write it out by image row/scanline, include
appropriate header and chunk info, and you're done.
Not quite. You need to encode it by scanline, add the filter byte at the beginning of
each line, _then_ zlib compress it. The filter byte can just be 0 throughout if you don't
want to worry about filtering.
If you just want a basic truecolour or greyscale PNG encoder, then it's a
matter of:
- write the PNG signature
- write the IHDR, being careful about byte order
- write the IDAT - zlib compressed image data
- write the IEND
You also need to compute the CRC of each chunk, but std.zlib has a function to do that as
well.
FWIW a while ago I wrote a simple experimental program that generates an image and encodes
it as a PNG. And I've just tweaked it and updated it to D2 (attached). It supports only
truecolour with 8 bits per sample, but it supports filtering, though it isn't adaptive
(you just specify the filter to use when you run the program).
Stewart.
import
std.file,
std.math,
std.path,
std.stdio,
std.zlib;
const ubyte[] header = [ 137, 80, 78, 71, 13, 10, 26, 10 ];
const uint WIDTH = 100, HEIGHT = 100;
align(1) struct IHDR {
uint width = WIDTH;
uint height = HEIGHT;
ubyte bitDepth = 8;
ubyte colourType = 2;
ubyte compressMethod, filterMethod, interlaceMethod;
version (LittleEndian) {
IHDR bigEndian() {
IHDR result = this;
result.width = .bigEndian(width);
result.height = .bigEndian(height);
return result;
}
} else {
ref IHDR bigEndian() { return this; }
}
}
align(1) struct RGB {
ubyte red, green, blue;
}
void main(string[] a) {
ubyte filterType;
string outputFile = "makepng.png";
if (a.length > 1 && a[1].length == 1 && a[1][0] >= '0' && a[1][0] <=
'4') {
filterType = cast(ubyte) (a[1][0] - '0');
a = a[1..$];
}
if (a.length > 1) {
outputFile = defaultExtension(a[1], "png");
}
void[] pngData = header.dup;
pngData ~= makeChunk("IHDR", IHDR.init.bigEndian);
RGB[HEIGHT][WIDTH] imageData;
foreach (y, ref scanline; imageData) {
foreach (x, ref pixel; scanline) {
if ((x-50) * (x-50) + (y-50) * (y-50) < 2000) {
pixel.red = 255;
pixel.green = cast(ubyte) (2 * x);
pixel.blue = cast(ubyte) (255 * y / 100);
}
}
}
ubyte[] imageData2;
if (filterType == 0) {
foreach (y, ref scanLine; imageData) {
imageData2 ~= 0;
imageData2 ~= cast(ubyte[]) scanLine;
}
} else {
Predictor predictor = predictors[filterType];
ubyte[] prevLine, thisLine;
prevLine.length = 3 * (WIDTH + 1);
thisLine.length = 3 * (WIDTH + 1);
foreach (y, ref scanLine; imageData) {
thisLine[3..$] = cast(ubyte[]) scanLine;
imageData2 ~= filterType;
for (uint x = 0; x < 3 * WIDTH; x++) {
imageData2 ~= cast(ubyte) (thisLine[x + 3]
- predictor(thisLine[x], prevLine[x+3],
prevLine[x]));
}
ubyte[] tempLine = prevLine;
prevLine = thisLine;
thisLine = tempLine;
}
}
assert (imageData2.length == (3 * WIDTH + 1) * HEIGHT);
pngData ~= makeChunkV("IDAT", compress(imageData2));
writeln(pngData.length);
pngData ~= makeChunkV("IEND", null);
std.file.write(outputFile, pngData);
}
version (LittleEndian) {
uint bigEndian(uint value) {
return (value << 24) | ((value & 0xFF00) << 8)
| ((value & 0x00FF) >> 8) | (value >> 24);
}
} else {
uint bigEndian(uint value) { return value; }
}
void[] bigEndianBytes(uint value) {
uint[] be = [bigEndian(value)];
return be;
}
void[] makeChunkV(in string type, in void[] data)
in {
assert(type.length == 4);
} body {
void[] typeAndData = type ~ data;
uint crc = crc32(0, typeAndData);
return bigEndianBytes(data.length) ~ typeAndData ~ bigEndianBytes(crc);
}
void[] makeChunk(T)(in string type, in T data) {
static assert (!is(T : void[]));
return makeChunkV(type, cast(void[]) (&data)[0..1]);
}
// FILTER PREDICTOR FUNCT
Re: JPG and PNG decoder
Am 16.06.2012 21:10, schrieb cal: I've been working on decoders for simple (baseline) JPEG and PNG's, mostly for my own amusement, and they seem to work ok now, so if anyone has need of some simple D modules to load these formats you can grab them here: https://github.com/callumenator/imaged Notes: - Will load 8-bit baseline sequential JPEG's only. All PNG image types are supported (only critical chunks are decoded however). - Can load from a stream or a file. In the case of the PNG's, this allows progressive display with an interlaced image. - I haven't put much effort into speeding up these routines, and have not tested the JPEG decoder extensively, so there are bound to be bugs and there is plenty room for improvement. - The example shows stream usage, and uses Adam Ruppe's simpledisplay to make a little viewer, that can flick through all images in a directory. Cheers, cal Cool so I don't need to use my stb_image binding ( https://bitbucket.org/dav1d/gl-utils/src/0b97f77c14d7/stb_image ) anylonger!
Re: JPG and PNG decoder
On Sun, Jun 17, 2012 at 9:55 AM, cal wrote: > On Sunday, 17 June 2012 at 07:07:35 UTC, Philippe Sigaud wrote: >> >> Still, I'm interested in writing a JPEG/PNG to disk from a >> ubyte[3][][], or whatever. > > > Do you mean that you want to encode a ubyte array to disk as JPEG/PNG? > Encoding a JPEG would be a bit of work I think, the format's kind of a > monster. PNG should be easier, depending on how good you want the > compression to be. If you don't care too much about compression level, you > simply zlib compress the data, write it out by image row/scanline, include > appropriate header and chunk info, and you're done. I'll give a simple > encoder a go if you think you could use it. Years ago, one of the first programs I did in D was a raytracer. It was a good test for OOP, structs, 3D vectors, foreach loops (which were all the rage 4-5 years ago, even before ranges). It was nice and fun, but I then discovered that, at the time, I had no easy way to write my pixel 2D arrays to disk. I had to code a small BMP writer. Nowdays, I'm playing with the idea to write a new tutorial for D, using a raytracer and new D technics like CTFE / templates / std.algorithms. This time, I would like to save the images as JPEG / PNG. I guess it's possible to wrap some C lib to do the work, but it's be nice to have a D module to do that. Anyway, nice work with the loader!
Re: JPG and PNG decoder
cal: I've been working on decoders for simple (baseline) JPEG and PNG's, mostly for my own amusement, and they seem to work ok now, so if anyone has need of some simple D modules to load these formats you can grab them here: https://github.com/callumenator/imaged Suggestions on the code: - Try to use final switches. - switch cases don't need (), so instead of case(foo): write case foo: - Try to add const/immutable/pure/nothrow where possible. Bye, bearophile
Re: JPG and PNG decoder
I second the request for a PNG encoder. You just saved me a lot of trouble, as I was about to implement my own PNG loader... and now I don't have to. ^_^ I'll glance over your code in full sometime and see if I notice any readily apparent improvements.
Re: JPG and PNG decoder
On Sunday, 17 June 2012 at 07:07:35 UTC, Philippe Sigaud wrote: Still, I'm interested in writing a JPEG/PNG to disk from a ubyte[3][][], or whatever. Do you mean that you want to encode a ubyte array to disk as JPEG/PNG? Encoding a JPEG would be a bit of work I think, the format's kind of a monster. PNG should be easier, depending on how good you want the compression to be. If you don't care too much about compression level, you simply zlib compress the data, write it out by image row/scanline, include appropriate header and chunk info, and you're done. I'll give a simple encoder a go if you think you could use it. Cheers, cal
Re: JPG and PNG decoder
On Sun, Jun 17, 2012 at 8:15 AM, Philippe Sigaud wrote: >> I've been working on decoders for simple (baseline) JPEG and PNG's, mostly >>so if anyone has need of some simple D modules to load these formats you can >>grab them here: > Is there a way to write an Image to disk? I didn't see one while > skimming the source. Oops, you*did* say these where for loading. Sorry for the noise :) Still, I'm interested in writing a JPEG/PNG to disk from a ubyte[3][][], or whatever.
Re: JPG and PNG decoder
> On 6/16/2012 12:10 PM, cal wrote: >> >> I've been working on decoders for simple (baseline) JPEG and PNG's, mostly >> for >> my own amusement, and they seem to work ok now, so if anyone has need of >> some >> simple D modules to load these formats you can grab them here: >> https://github.com/callumenator/imaged Nice one, thanks. Is there a way to write an Image to disk? I didn't see one while skimming the source.
Re: JPG and PNG decoder
On 6/16/2012 12:10 PM, cal wrote: I've been working on decoders for simple (baseline) JPEG and PNG's, mostly for my own amusement, and they seem to work ok now, so if anyone has need of some simple D modules to load these formats you can grab them here: https://github.com/callumenator/imaged Thank you!
JPG and PNG decoder
I've been working on decoders for simple (baseline) JPEG and PNG's, mostly for my own amusement, and they seem to work ok now, so if anyone has need of some simple D modules to load these formats you can grab them here: https://github.com/callumenator/imaged Notes: - Will load 8-bit baseline sequential JPEG's only. All PNG image types are supported (only critical chunks are decoded however). - Can load from a stream or a file. In the case of the PNG's, this allows progressive display with an interlaced image. - I haven't put much effort into speeding up these routines, and have not tested the JPEG decoder extensively, so there are bound to be bugs and there is plenty room for improvement. - The example shows stream usage, and uses Adam Ruppe's simpledisplay to make a little viewer, that can flick through all images in a directory. Cheers, cal
