cfeck / imagezero Goto Github PK
View Code? Open in Web Editor NEWFast Lossless Color Image Compression Library
License: BSD 2-Clause "Simplified" License
Fast Lossless Color Image Compression Library
License: BSD 2-Clause "Simplified" License
ImageZero is a high-performance lossless RGB color image compressor/decompressor. Compared to PNG, it compresses 24 bit PPM files about 20 times faster, and decompresses to PPM about 2 times faster, while the compression rate is nearly as good as PNG for natural photos. ImageZero is not suited for “flat” (computer generated) graphics or grayscale images. The code is “early work in progress”, and neither the image format, nor the library API are fully outlined yet. To contact the author, see the AUTHORS file. Any feedback is appreciated.
Please Show Me The Implementation
I want to use this in my own code
How Can I Use This
Kindly Show The Implementation of this project because it is show hard to understand file directory
Anyway The Code and complexity acc. to me is much much good than other
appreciate your hardwork
it would be beneficial if you show us Implementation
Hi,
macOS compilation error has been fixed.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index a88fc42..8ddb9e8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,7 +14,12 @@ set(iz_SRCS
add_definitions(-DHAVE_MMAP)
-set(CMAKE_EXE_LINKER_FLAGS "-Wl,-O1,-s,--no-export-dynamic")
+
+if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+ set(CMAKE_EXE_LINKER_FLAGS "-Wl,-O1,-s,--no-export-dynamic")
+else()
+ set(CMAKE_EXE_LINKER_FLAGS "")
+endif()
set(CMAKE_CXX_FLAGS_RELEASE "-O2 -mmmx -mtune=atom -Winline -W -Wall -fomit-frame-pointer -fno-rtti -fno-exceptions")
add_executable(iz ${iz_SRCS})
diff --git a/file.cpp b/file.cpp
index 53a295a..cfdb3a0 100644
--- a/file.cpp
+++ b/file.cpp
@@ -14,6 +14,16 @@
#include <sys/mman.h>
#include <sys/stat.h>
+#if (defined(__APPLE__) && defined(__MACH__))
+# if defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
+# define __PLATFORM_IOS__
+# else
+# define __PLATFORM_MACOS__
+# endif
+#elif defined(macintosh) || defined(Macintosh)
+# define __PLATFORM_MACOS__
+#endif
+
class InputFile::Private
{
public:
@@ -31,7 +41,11 @@ InputFile::InputFile(const char *filename)
struct stat sb;
fstat(fd, &sb);
d->size = sb.st_size;
+#if defined(__PLATFORM_MACOS__)
+ d->addr = mmap(0, d->size, PROT_READ, MAP_PRIVATE, fd, 0);
+#else
d->addr = mmap(0, d->size, PROT_READ, MAP_PRIVATE | MAP_POPULATE, fd, 0);
+#endif
if (d->addr == MAP_FAILED) {
d->addr = mmap(0, d->size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (d->addr != MAP_FAILED) {
what do you think?
P.S. Please understand that I am not good at English.
Hi Christoph, I was trying to understand how IZ does its magic and stumbled upon the code in table.cpp
that I found interesting and struggle to understand completely.
I understood that you use CONTEXT_BITS = 4
to store the integer values 0..8 (so CONTEXT_COUNT = 9
) that encode how many bits are used to code each color channel of a given pixel.
But what I struggle to understand is the meaning of MAX_CODE_LENGTH = 6
, and how are the entries of staticdCount
are chosen and then used to calculate the entries of staticdBits
(for encoding) and decodeTable
(for decoding). I figured out that you code the current context depending on the last one, but why and how exactly is this done?
Is this a standard approach that I am not aware of? Or have you explained the idea somewhere else?
Any further information is appreciated!
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