There is no class or function called vil_property. More...
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Defines | |
| #define | vil_property_memory "memory" |
| Indicate whether this is an in-memory image or an on-disk image. | |
| #define | vil_property_read_only "read-only" |
| Indicate that you can't call put_view on this image. | |
| #define | vil_property_pixel_size "pixel_size" |
| Pixel width in metres. | |
| #define | vil_property_offset "offset" |
| Original image origin in pixels. | |
| #define | vil_property_quantisation_depth "quantisation_depth" |
| The quantisation depth of pixel components. | |
| #define | vil_property_size_block_i "size_block_i" |
| For unblocked images, the following properties are not implemented. | |
| #define | vil_property_size_block_j "size_block_j" |
| Block size in rows. | |
| #define | vil_property_pyramid "pyramid" |
| true if image resource is a pyramid image. | |
There is no class or function called vil_property.
The image class vil_image_resource has the method :
bool get_property(char const *tag, void *property_value = 0) const;
which allow format extensions to be added without cluttering the interface to vil_image_resource. The idea is that properties can be identified by a "tag" (some name or other textual description) through which clients can obtain or manipulate extra properties.
A false return value means that the underlying image does not understand the given property or that the given data was invalid. A true return value means it does understand the property and has used the supplied data according to the relevant protocol. Passing a null pointer as the second argument can be useful for protocols for manipulating boolean properties (i.e. when there is no data to be passed).
To make this work in practice, it is necessary to avoid name clashes and to make sure everyone agrees on the meaning of the property data. That is the purpose of this file. The set of tags is a namespace in the general sense of the word. We only have one namespace, so try not to clutter it. All property tags described in this file should begin with "vil_property_" and that chunk of the namespace is reserved.
Definition in file vil_property.h.
| #define vil_property_memory "memory" |
Indicate whether this is an in-memory image or an on-disk image.
By default an image is not in-memory, and since this is a boolean property the return value of get_property(), which is "false" by default, will be correct. Only in-memory images must implement this property, and return "true".
Definition at line 40 of file vil_property.h.
| #define vil_property_offset "offset" |
Original image origin in pixels.
Measured right from left edge, and down from top - i.e. in i and j directions Type is float[2].
Definition at line 58 of file vil_property.h.
| #define vil_property_pixel_size "pixel_size" |
Pixel width in metres.
Strictly this is the pixel spacing, and not some function of the sensor's spatial sampling kernel. Type is float[2].
Definition at line 53 of file vil_property.h.
| #define vil_property_pyramid "pyramid" |
true if image resource is a pyramid image.
Definition at line 82 of file vil_property.h.
| #define vil_property_quantisation_depth "quantisation_depth" |
The quantisation depth of pixel components.
This is the maximum information per pixel component. (Bear in mind that particular image may not even be using all of it.) e.g. an image with true vil_rgb<vxl_byte> style pixels would return 8. If a file image has this property implemented, and purports to supply an unsigned-type you can assume that it will give you pixels valued between 0 and 2^quantisation_depth - 1. Type is unsigned int.
Definition at line 67 of file vil_property.h.
| #define vil_property_read_only "read-only" |
Indicate that you can't call put_view on this image.
By default an image is not read-only, and since this is a boolean property the return value of get_property(), which is "false" by default, will be correct. Only images which do not allow put_view must implement this property, and return "true".
Definition at line 47 of file vil_property.h.
| #define vil_property_size_block_i "size_block_i" |
For unblocked images, the following properties are not implemented.
It is assumed that all blocks are the same size and padded with zeros if necessary. Thus, n_block_i = (ni() + size_block_i - 1)/size_block_i and n_block_j = (nj() + size_block_j - 1)/size_block_j. Both properties must be implemented for blocked images. Type is unsigned int. Block size in columns.
Definition at line 76 of file vil_property.h.
| #define vil_property_size_block_j "size_block_j" |
Block size in rows.
Definition at line 79 of file vil_property.h.
1.7.5.1