Image Interpolation with Contour Stencils
Defines | Functions

imageio.h File Reference

Implements ReadImage and WriteImage functions. More...

#include <stdio.h>
#include "basic.h"
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Defines

#define MAX_IMAGE_SIZE   10000
 Limit on the maximum allowed image width or height (security).
#define SUPPORTEDSTRING_JPEG   ""
#define SUPPORTEDSTRING_PNG   ""
#define SUPPORTEDSTRING_TIFF   ""
#define READIMAGE_FORMATS_SUPPORTED   "BMP" SUPPORTEDSTRING_JPEG SUPPORTEDSTRING_PNG SUPPORTEDSTRING_TIFF
#define WRITEIMAGE_FORMATS_SUPPORTED   "BMP" SUPPORTEDSTRING_JPEG SUPPORTEDSTRING_PNG SUPPORTEDSTRING_TIFF
#define IMAGEIO_U8   0x0000
#define IMAGEIO_SINGLE   0x0001
#define IMAGEIO_FLOAT   IMAGEIO_SINGLE
#define IMAGEIO_DOUBLE   0x0002
#define IMAGEIO_STRIP_ALPHA   0x0010
#define IMAGEIO_BGRFLIP   0x0020
#define IMAGEIO_AFLIP   0x0040
#define IMAGEIO_GRAYSCALE   0x0080
#define IMAGEIO_PLANAR   0x0100
#define IMAGEIO_COLUMNMAJOR   0x0200
#define IMAGEIO_RGB   (IMAGEIO_STRIP_ALPHA)
#define IMAGEIO_BGR   (IMAGEIO_STRIP_ALPHA | IMAGEIO_BGRFLIP)
#define IMAGEIO_RGBA   0x0000
#define IMAGEIO_BGRA   (IMAGEIO_BGRFLIP)
#define IMAGEIO_ARGB   (IMAGEIO_AFLIP)
#define IMAGEIO_ABGR   (IMAGEIO_BGRFLIP | IMAGEIO_AFLIP)
#define _CRT_SECURE_NO_WARNINGS
 Avoid MSVC warnings on using fopen.

Functions

int IdentifyImageType (char *Type, const char *FileName)
 Identify the file type of an image file by its magic numbers.
void * ReadImage (int *Width, int *Height, const char *FileName, unsigned Format)
 Read an image file as 32-bit RGBA data.
int WriteImage (void *Image, int Width, int Height, const char *FileName, unsigned Format, int Quality)
 Write an image file from 8-bit RGBA image data.

Detailed Description

Implements ReadImage and WriteImage functions.

Author:
Pascal Getreuer <getreuer@gmail.com>

Copyright (c) 2010-2011, Pascal Getreuer All rights reserved.

This program is free software: you can use, modify and/or redistribute it under the terms of the simplified BSD License. You should have received a copy of this license along this program. If not, see <http://www.opensource.org/licenses/bsd-license.html>.

Definition in file imageio.h.


Define Documentation

#define _CRT_SECURE_NO_WARNINGS

Avoid MSVC warnings on using fopen.

Definition at line 75 of file imageio.h.

#define IMAGEIO_ABGR   (IMAGEIO_BGRFLIP | IMAGEIO_AFLIP)

Definition at line 71 of file imageio.h.

#define IMAGEIO_AFLIP   0x0040

Definition at line 62 of file imageio.h.

#define IMAGEIO_ARGB   (IMAGEIO_AFLIP)

Definition at line 70 of file imageio.h.

#define IMAGEIO_BGR   (IMAGEIO_STRIP_ALPHA | IMAGEIO_BGRFLIP)

Definition at line 67 of file imageio.h.

#define IMAGEIO_BGRA   (IMAGEIO_BGRFLIP)

Definition at line 69 of file imageio.h.

#define IMAGEIO_BGRFLIP   0x0020

Definition at line 61 of file imageio.h.

#define IMAGEIO_COLUMNMAJOR   0x0200

Definition at line 65 of file imageio.h.

#define IMAGEIO_DOUBLE   0x0002

Definition at line 59 of file imageio.h.

#define IMAGEIO_FLOAT   IMAGEIO_SINGLE

Definition at line 58 of file imageio.h.

#define IMAGEIO_GRAYSCALE   0x0080

Definition at line 63 of file imageio.h.

#define IMAGEIO_PLANAR   0x0100

Definition at line 64 of file imageio.h.

#define IMAGEIO_RGB   (IMAGEIO_STRIP_ALPHA)

Definition at line 66 of file imageio.h.

#define IMAGEIO_RGBA   0x0000

Definition at line 68 of file imageio.h.

#define IMAGEIO_SINGLE   0x0001

Definition at line 57 of file imageio.h.

#define IMAGEIO_STRIP_ALPHA   0x0010

Definition at line 60 of file imageio.h.

#define IMAGEIO_U8   0x0000

Definition at line 56 of file imageio.h.

#define MAX_IMAGE_SIZE   10000

Limit on the maximum allowed image width or height (security).

Definition at line 23 of file imageio.h.

#define READIMAGE_FORMATS_SUPPORTED   "BMP" SUPPORTEDSTRING_JPEG SUPPORTEDSTRING_PNG SUPPORTEDSTRING_TIFF

String macro listing supported formats for ReadImage. For example,

    printf("Supported formats for reading: " READIMAGE_FORMATS_SUPPORTED ".\n");

Definition at line 47 of file imageio.h.

#define SUPPORTEDSTRING_JPEG   ""

Definition at line 29 of file imageio.h.

#define SUPPORTEDSTRING_PNG   ""

Definition at line 34 of file imageio.h.

#define SUPPORTEDSTRING_TIFF   ""

Definition at line 39 of file imageio.h.

#define WRITEIMAGE_FORMATS_SUPPORTED   "BMP" SUPPORTEDSTRING_JPEG SUPPORTEDSTRING_PNG SUPPORTEDSTRING_TIFF

String macro listing supported formats for WriteImage

Definition at line 51 of file imageio.h.


Function Documentation

int IdentifyImageType ( char *  Type,
const char *  FileName 
)

Identify the file type of an image file by its magic numbers.

Parameters:
Typedestination buffer with space for at least 5 chars
FileNameimage file name
Returns:
1 on successful identification, 0 on failure.

The routine fills Type with an identifying string. If there is an error or the file type is unknown, Type is set to a null string.

Definition at line 1842 of file imageio.c.

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void* ReadImage ( int *  Width,
int *  Height,
const char *  FileName,
unsigned  Format 
)

Read an image file as 32-bit RGBA data.

Parameters:
Width,Heightpointers to be filled with the image dimensions
FileNameimage file name
Formatspecifies the desired format for the image
Returns:
Pointer to the image data, or null on failure

The calling syntax is that the filename is the input and Width, and Height and the returned pointer are outputs. ReadImage allocates memory for the image as one contiguous block of memory and returns a pointer. It is the responsibility of the caller to call Free on this pointer when done to release this memory.

A non-null pointer indicates success. On failure, the returned pointer is null, and Width and Height are set to 0.

The Format argument is used by specifying one of the data type options

  • IMAGEIO_U8: unsigned 8-bit components
  • IMAGEIO_SINGLE: float components
  • IMAGEIO_DOUBLE: double components

and one of the channel options

  • IMAGEIO_GRAYSCALE: grayscale data
  • IMAGEIO_RGB: RGB color data (red is the first channel)
  • IMAGEIO_BGR: BGR color data (blue is the first channel)
  • IMAGEIO_RGBA: RGBA color+alpha data
  • IMAGEIO_BGRA: BGRA color+alpha data
  • IMAGEIO_ARGB: ARGB color+alpha data
  • IMAGEIO_ABGR: ABGR color+alpha data

and optionally either or both of the ordering options

  • IMAGEIO_PLANAR: planar order instead of interleaved components
  • IMAGEIO_COLUMNMAJOR: column major order instead of row major order
    uint32_t *Image;
    int Width, Height;
    
    if(!(Image = (uint32_t *)ReadImage(&Width, &Height, "myimage.bmp", 
        IMAGEIO_U8 | IMAGEIO_RGBA)))
        return 0;
    
    printf("Read image of size %dx%d\n", Width, Height);
    
    ...
    
    Free(Image);

With the default formatting IMAGEIO_U8 | IMAGEIO_RGBA, the image is organized in standard row major top-down 32-bit RGBA order. The image is organized as

    (Top left)                                             (Top right)
    Image[0]                Image[1]        ...  Image[Width-1]
    Image[Width]            Image[Width+1]  ...  Image[2*Width]
    ...                     ...             ...  ...
    Image[Width*(Height-1)] ...             ...  Image[Width*Height-1]
    (Bottom left)                                       (Bottom right)

Each element Image[k] represents one RGBA pixel, which is a 32-bit bitfield. The components of pixel Image[k] can be unpacked as

    uint8_t *Component = (uint8_t *)&Image[k];
    uint8_t Red = Component[0];
    uint8_t Green = Component[1];
    uint8_t Blue = Component[2];
    uint8_t Alpha = Component[3];

Each component is an unsigned 8-bit integer value with range 0-255. Most images do not have alpha information, in which case the alpha component is set to value 255 (full opacity).

With IMAGEIO_SINGLE or IMAGEIO_DOUBLE, the components are values in the range 0 to 1.

Definition at line 1971 of file imageio.c.

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int WriteImage ( void *  Image,
int  Width,
int  Height,
const char *  FileName,
unsigned  Format,
int  Quality 
)

Write an image file from 8-bit RGBA image data.

Parameters:
Imagepointer to the image data
Width,Heightimage dimensions
FileNameimage file name
Formatspecifies how the data is formatted (see ReadImage)
Qualitythe JPEG image quality (between 0 and 100)
Returns:
1 on success, 0 on failure

The input Image should be a 32-bit RGBA image stored as in the description of ReadImage. WriteImage writes to FileName in the file format specified by its extension. If saving a JPEG image, the Quality argument specifies the quality factor (between 0 and 100). Quality has no effect on other formats.

The return value indicates success with 1 or failure with 0.

Definition at line 2074 of file imageio.c.

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