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Add imread()
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‎src/imgcodecs.cpp

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// C++ headers
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#include "opencv2/core.hpp"
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#include "opencv2/imgcodecs.hpp"
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#include "convert.h"
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#include "numpy.h"
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// C headers
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extern "C" {
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#include "imgcodecs.h"
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#include "ulab/code/ndarray.h"
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#include "py/builtin.h"
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} // extern "C"
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using namespace cv;
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// Helper macro to create an empty mp_map_t, derived from MP_DEFINE_CONST_MAP.
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// Primarily used for function calls with no keyword arguments, since we can't
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// just pass `NULL` or mp_const_none (crash occurs otherwise)
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#define MP_EMPTY_MAP() { \
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.all_keys_are_qstrs = 0, \
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.is_fixed = 1, \
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.is_ordered = 0, \
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.used = 0, \
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.alloc = 0, \
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.table = (mp_map_elem_t *)(mp_rom_map_elem_t *)mp_const_none, \
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}
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mp_obj_t cv2_imgcodecs_imread(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
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// Define the arguments
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enum { ARG_filename, ARG_flags };
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static const mp_arg_t allowed_args[] = {
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{ MP_QSTR_filename, MP_ARG_REQUIRED | MP_ARG_OBJ, { .u_obj = MP_OBJ_NULL } },
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{ MP_QSTR_flags, MP_ARG_INT, { .u_int = IMREAD_COLOR_BGR } },
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};
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// Parse the arguments
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mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
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mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
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// Convert arguments to required types
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mp_obj_t filename = args[ARG_filename].u_obj;
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int flags = args[ARG_flags].u_int;
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// Call MicroPython's `open()` function to read the image file
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mp_obj_t open_args[2];
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open_args[0] = filename;
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open_args[1] = mp_obj_new_str("rb", 2); // Open in binary read mode
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mp_map_t open_kw_args = MP_EMPTY_MAP(); // No keyword arguments
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mp_obj_t file_obj = mp_builtin_open(2, open_args, &open_kw_args);
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// Call the `read()` method on the file object to get the image data
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mp_obj_t read_method[2];
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mp_load_method(file_obj, MP_QSTR_read, read_method);
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mp_obj_t bytes_obj = mp_call_method_n_kw(0, 0, read_method);
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// Close the file object
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mp_obj_t close_method[2];
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mp_load_method(file_obj, MP_QSTR_close, close_method);
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mp_call_method_n_kw(0, 0, close_method);
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// Convert bytes_obj to vector of uint8_t for decoding
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size_t len;
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const char *buf_data = mp_obj_str_get_data(bytes_obj, &len);
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std::vector<uint8_t> buf(buf_data, buf_data + len);
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// Decode the image from the buffer
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Mat img;
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try {
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img = imdecode(buf, flags);
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} catch(Exception& e) {
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mp_raise_msg(&mp_type_Exception, MP_ERROR_TEXT(e.what()));
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}
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// Return the image
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return mat_to_mp_obj(img);
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}

‎src/imgcodecs.h

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// C headers
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#include "py/runtime.h"
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extern mp_obj_t cv2_imgcodecs_imread(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args);

‎src/opencv_upy.c

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#include "core.h"
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#include "highgui.h"
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#include "imgproc.h"
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#include "imgcodecs.h"
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////////////////////////////////////////////////////////////////////////////////
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// Python references to OpenCV functions
@@ -14,6 +15,9 @@ static MP_DEFINE_CONST_FUN_OBJ_KW(cv2_core_inRange_obj, 3, cv2_core_inRange);
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static MP_DEFINE_CONST_FUN_OBJ_KW(cv2_highgui_imshow_obj, 2, cv2_highgui_imshow);
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static MP_DEFINE_CONST_FUN_OBJ_KW(cv2_highgui_waitKey_obj, 0, cv2_highgui_waitKey);
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// OpenCV imgcodecs module
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static MP_DEFINE_CONST_FUN_OBJ_KW(cv2_imgcodecs_imread_obj, 1, cv2_imgcodecs_imread);
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// OpenCV imgproc module
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static MP_DEFINE_CONST_FUN_OBJ_KW(cv2_imgproc_adaptiveThreshold_obj, 6, cv2_imgproc_adaptiveThreshold);
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static MP_DEFINE_CONST_FUN_OBJ_KW(cv2_imgproc_arrowedLine_obj, 4, cv2_imgproc_arrowedLine);
@@ -88,6 +92,23 @@ static const mp_rom_map_elem_t cv2_module_globals_table[] = {
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{ MP_ROM_QSTR(MP_QSTR_BORDER_DEFAULT), MP_ROM_INT(4) },
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{ MP_ROM_QSTR(MP_QSTR_BORDER_ISOLATED), MP_ROM_INT(16) },
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// Image read mode flags, from opencv2/imgcodecs.hpp
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_UNCHANGED), MP_ROM_INT(-1) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_GRAYSCALE), MP_ROM_INT(0) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_COLOR_BGR), MP_ROM_INT(1) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_COLOR), MP_ROM_INT(1) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_ANYDEPTH), MP_ROM_INT(2) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_ANYCOLOR), MP_ROM_INT(4) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_LOAD_GDAL), MP_ROM_INT(8) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_REDUCED_GRAYSCALE_2), MP_ROM_INT(16) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_REDUCED_COLOR_2), MP_ROM_INT(17) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_REDUCED_GRAYSCALE_4), MP_ROM_INT(32) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_REDUCED_COLOR_4), MP_ROM_INT(33) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_REDUCED_GRAYSCALE_8), MP_ROM_INT(64) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_REDUCED_COLOR_8), MP_ROM_INT(65) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_IGNORE_ORIENTATION), MP_ROM_INT(128) },
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{ MP_ROM_QSTR(MP_QSTR_IMREAD_COLOR_RGB), MP_ROM_INT(256) },
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// Morphology operation types, from opencv2/imgproc.hpp
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{ MP_ROM_QSTR(MP_QSTR_MORPH_ERODE), MP_ROM_INT(0) },
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{ MP_ROM_QSTR(MP_QSTR_MORPH_DILATE), MP_ROM_INT(1) },
@@ -223,6 +244,12 @@ static const mp_rom_map_elem_t cv2_module_globals_table[] = {
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{ MP_ROM_QSTR(MP_QSTR_imshow), MP_ROM_PTR(&cv2_highgui_imshow_obj) },
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{ MP_ROM_QSTR(MP_QSTR_waitKey), MP_ROM_PTR(&cv2_highgui_waitKey_obj) },
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////////////////////////////////////////////////////////////////////////////
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// OpenCV imgcodecs functions
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////////////////////////////////////////////////////////////////////////////
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{ MP_ROM_QSTR(MP_QSTR_imread), MP_ROM_PTR(&cv2_imgcodecs_imread_obj) },
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////////////////////////////////////////////////////////////////////////////
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// OpenCV imgproc functions

‎src/opencv_upy.cmake

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${CMAKE_CURRENT_LIST_DIR}/convert.cpp
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${CMAKE_CURRENT_LIST_DIR}/core.cpp
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${CMAKE_CURRENT_LIST_DIR}/highgui.cpp
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${CMAKE_CURRENT_LIST_DIR}/imgcodecs.cpp
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${CMAKE_CURRENT_LIST_DIR}/imgproc.cpp
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${CMAKE_CURRENT_LIST_DIR}/numpy.cpp
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${CMAKE_CURRENT_LIST_DIR}/opencv_upy.c

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