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PNMImageHeader Class Reference

This is the base class of PNMImage, PNMReader, and PNMWriter. More...

Inheritance diagram for PNMImageHeader:
PfmFile PNMImage

Classes

class  Histogram
 
class  PixelSpec
 
class  PixelSpecCount
 

Public Types

enum  ColorType {
  CT_invalid = 0, CT_grayscale = 1, CT_two_channel = 2, CT_color = 3,
  CT_four_channel = 4
}
 

Public Member Functions

 __init__ ()
 
 __init__ (const PNMImageHeader copy)
 
ColorSpace getColorSpace ()
 Returns the color space that the image is encoded in, or CS_unspecified if unknown. More...
 
PNMImageHeader::ColorType getColorType ()
 Returns the image type of the image, as an enumerated value. More...
 
str getComment ()
 Gets the user comment from the file. More...
 
Xelval getMaxval ()
 Returns the maximum channel value allowable for any pixel in this image; for instance, 255 for a typical 8-bit-per-channel image. More...
 
int getNumChannels ()
 Returns the number of channels in the image. More...
 
LVecBase2i getSize ()
 Returns the number of pixels in each direction. More...
 
PNMFileType getType ()
 If the file type is known (e.g. More...
 
int getXSize ()
 Returns the number of pixels in the X direction. More...
 
int getYSize ()
 Returns the number of pixels in the Y direction. More...
 
bool hasAlpha ()
 Returns true if the image includes an alpha channel, false otherwise. More...
 
bool hasType ()
 Returns true if the PNMImageHeader knows what type it is, false otherwise. More...
 
bool isGrayscale ()
 Returns false if the image is a full-color image, and has red, green, and blue components; true if it is a grayscale image and has only a gray component. More...
 
PNMReader makeReader (const Filename filename, PNMFileType type, bool report_unknown_type)
 Returns a newly-allocated PNMReader of the suitable type for reading from the indicated image filename, or NULL if the filename cannot be read for some reason. More...
 
PNMReader makeReader (Istream file, bool owns_file, const Filename filename, str magic_number, PNMFileType type, bool report_unknown_type)
 Returns a newly-allocated PNMReader of the suitable type for reading from the already-opened image file, or NULL if the file cannot be read for some reason. More...
 
PNMWriter makeWriter (const Filename filename, PNMFileType type)
 Returns a newly-allocated PNMWriter of the suitable type for writing an image to the indicated filename, or NULL if the filename cannot be written for some reason. More...
 
PNMWriter makeWriter (Ostream file, bool owns_file, const Filename filename, PNMFileType type)
 Returns a newly-allocated PNMWriter of the suitable type for writing to the already-opened image file, or NULL if the file cannot be written for some reason. More...
 
PNMImageHeader operator= (const PNMImageHeader copy)
 
 output (Ostream out)
 
bool readHeader (const Filename filename, PNMFileType type, bool report_unknown_type)
 Opens up the image file and tries to read its header information to determine its size, number of channels, etc. More...
 
bool readHeader (Istream data, str filename, PNMFileType type, bool report_unknown_type)
 Reads the image header information only from the indicated stream. More...
 
 setComment (str comment)
 Writes a user comment string to the image (header). More...
 
 setType (PNMFileType type)
 Sets the file type of this PNMImage. More...
 

Static Public Member Functions

static bool hasAlpha (PNMImageHeader::ColorType color_type)
 This static variant of has_alpha() returns true if the indicated image type includes an alpha channel, false otherwise. More...
 
static bool isGrayscale (PNMImageHeader::ColorType color_type)
 This static variant of is_grayscale() returns true if the indicated image type represents a grayscale image, false otherwise. More...
 

Public Attributes

ColorSpace color_space
 Returns the color space that the image is encoded in, or CS_unspecified if unknown. More...
 
String comment
 Gets the user comment from the file. More...
 
Xelval maxval
 Returns the maximum channel value allowable for any pixel in this image; for instance, 255 for a typical 8-bit-per-channel image. More...
 
int num_channels
 Returns the number of channels in the image. More...
 
LVecBase2i size
 Returns the number of pixels in each direction. More...
 
PNMFileType type
 If the file type is known (e.g. More...
 

Detailed Description

This is the base class of PNMImage, PNMReader, and PNMWriter.

It encapsulates all the information associated with an image that describes its size, number of channels, etc; that is, all the information about the image except the image data itself. It's the sort of information you typically read from the image file's header.

Member Enumeration Documentation

◆ ColorType

enum ColorType
Enumerator
CT_invalid 
CT_grayscale 
CT_two_channel 
CT_color 
CT_four_channel 

Member Function Documentation

◆ __init__() [1/2]

__init__ ( )

◆ __init__() [2/2]

__init__ ( const PNMImageHeader  copy)

◆ getColorSpace()

ColorSpace getColorSpace ( )

Returns the color space that the image is encoded in, or CS_unspecified if unknown.

◆ getColorType()

PNMImageHeader::ColorType getColorType ( )

Returns the image type of the image, as an enumerated value.

This is really just the number of channels cast to the enumerated type.

◆ getComment()

str getComment ( )

Gets the user comment from the file.

◆ getMaxval()

Xelval getMaxval ( )

Returns the maximum channel value allowable for any pixel in this image; for instance, 255 for a typical 8-bit-per-channel image.

A pixel with this value is full on.

◆ getNumChannels()

int getNumChannels ( )

Returns the number of channels in the image.

◆ getSize()

LVecBase2i getSize ( )

Returns the number of pixels in each direction.

This is one more than the largest allowable coordinates.

◆ getType()

PNMFileType getType ( )

If the file type is known (e.g.

has_type() returns true), returns its PNMFileType pointer; otherwise, returns NULL.

◆ getXSize()

int getXSize ( )

Returns the number of pixels in the X direction.

This is one more than the largest allowable X coordinate.

◆ getYSize()

int getYSize ( )

Returns the number of pixels in the Y direction.

This is one more than the largest allowable Y coordinate.

◆ hasAlpha() [1/2]

bool hasAlpha ( )

Returns true if the image includes an alpha channel, false otherwise.

Unlike is_grayscale(), if this returns false it is an error to call any of the functions accessing the alpha channel.

◆ hasAlpha() [2/2]

static bool hasAlpha ( PNMImageHeader::ColorType  color_type)
static

This static variant of has_alpha() returns true if the indicated image type includes an alpha channel, false otherwise.

◆ hasType()

bool hasType ( )

Returns true if the PNMImageHeader knows what type it is, false otherwise.

◆ isGrayscale() [1/2]

bool isGrayscale ( )

Returns false if the image is a full-color image, and has red, green, and blue components; true if it is a grayscale image and has only a gray component.

(The gray color is actually stored in the blue channel, and the red and green channels are ignored.)

◆ isGrayscale() [2/2]

static bool isGrayscale ( PNMImageHeader::ColorType  color_type)
static

This static variant of is_grayscale() returns true if the indicated image type represents a grayscale image, false otherwise.

◆ makeReader() [1/2]

PNMReader makeReader ( const Filename  filename,
PNMFileType  type,
bool  report_unknown_type 
)

Returns a newly-allocated PNMReader of the suitable type for reading from the indicated image filename, or NULL if the filename cannot be read for some reason.

The filename "-" always stands for standard input. If type is specified, it is a suggestion for the file type to use.

The PNMReader should be deleted when it is no longer needed.

◆ makeReader() [2/2]

PNMReader makeReader ( Istream  file,
bool  owns_file,
const Filename  filename,
str  magic_number,
PNMFileType  type,
bool  report_unknown_type 
)

Returns a newly-allocated PNMReader of the suitable type for reading from the already-opened image file, or NULL if the file cannot be read for some reason.

owns_file should be set true if the PNMReader is to be considered the owner of the stream pointer (in which case the stream will be deleted on completion, whether successful or not), or false if it should not delete it.

The filename parameter is optional here, since the file has already been opened; it is only used to examine the extension and attempt to guess the file type.

If magic_number is nonempty, it is assumed to represent the first few bytes that have already been read from the file. Some file types may have difficulty if this is more than two bytes.

If type is non-NULL, it is a suggestion for the file type to use.

The PNMReader should be deleted when it is no longer needed.

◆ makeWriter() [1/2]

PNMWriter makeWriter ( const Filename  filename,
PNMFileType  type 
)

Returns a newly-allocated PNMWriter of the suitable type for writing an image to the indicated filename, or NULL if the filename cannot be written for some reason.

The filename "-" always stands for standard output. If type is specified, it is a suggestion for the file type to use.

The PNMWriter should be deleted when it is no longer needed.

◆ makeWriter() [2/2]

PNMWriter makeWriter ( Ostream  file,
bool  owns_file,
const Filename  filename,
PNMFileType  type 
)

Returns a newly-allocated PNMWriter of the suitable type for writing to the already-opened image file, or NULL if the file cannot be written for some reason.

owns_file should be set true if the PNMWriter is to be considered the owner of the stream pointer (in which case the stream will be deleted on completion, whether successful or not), or false if it should not delete it.

The filename parameter is optional here, since the file has already been opened; it is only used to examine the extension and attempt to guess the intended file type.

If type is non-NULL, it is a suggestion for the file type to use.

The PNMWriter should be deleted when it is no longer needed.

◆ operator=()

PNMImageHeader operator= ( const PNMImageHeader  copy)

◆ output()

output ( Ostream  out)

◆ readHeader() [1/2]

bool readHeader ( const Filename  filename,
PNMFileType  type,
bool  report_unknown_type 
)

Opens up the image file and tries to read its header information to determine its size, number of channels, etc.

If successful, updates the header information and returns true; otherwise, returns false.

◆ readHeader() [2/2]

bool readHeader ( Istream  data,
str  filename,
PNMFileType  type,
bool  report_unknown_type 
)

Reads the image header information only from the indicated stream.

The filename is advisory only, and may be used to suggest a type if it has a known extension.

If type is non-NULL, it is a suggestion for the type of file it is (and a non-NULL type will override any magic number test or filename extension lookup).

Returns true if successful, false on error.

◆ setComment()

setComment ( str  comment)

Writes a user comment string to the image (header).

◆ setType()

setType ( PNMFileType  type)

Sets the file type of this PNMImage.

This will be the default type used when an image is read, if the type cannot be determined by magic number or inferred by extension, or the type used when the image is written, if the type cannot be inferred from the filename extension.

Member Data Documentation

◆ color_space

ColorSpace color_space

Returns the color space that the image is encoded in, or CS_unspecified if unknown.

◆ comment

String comment

Gets the user comment from the file.

◆ maxval

Xelval maxval

Returns the maximum channel value allowable for any pixel in this image; for instance, 255 for a typical 8-bit-per-channel image.

A pixel with this value is full on.

◆ num_channels

int num_channels

Returns the number of channels in the image.

◆ size

LVecBase2i size

Returns the number of pixels in each direction.

This is one more than the largest allowable coordinates.

◆ type

If the file type is known (e.g.

has_type() returns true), returns its PNMFileType pointer; otherwise, returns NULL.