All RMagick constants are defined in the Magick
module.
Miscellaneous
constants |
MagickVersion |
The ×Magick version string. This has the
form:
@(#)ImageMagick X.Y.Z MM/DD/YY Q:16
http://www.imagemagick.org
or
GraphicsMagick 1.0 05/05/03 Q8
http://www.GraphicsMagick.org/ |
MaxRGB |
The maximum value of a Quantum . A
quantum is one of the red, green, blue, or opacity
elements of a pixel in the RGB colorspace, or cyan,
yellow, magenta, or black elements in the CYMK
colorspace. If ×Magick is built using
-DQuantumDepth=16, then MaxRGB is 65535, otherwise
it is 255. |
QuantumDepth |
The number of bits in a quantum. If
×Magick is built using -DQuantumDepth=16,
then QuantumDepth is 16, otherwise it is 8. |
Version |
The RMagick version string. This has the
form:
RMagick X.Y.Z |
|
|
ChannelType - see Image#channel |
UndefinedChannel |
RedChannel |
GreenChannel |
BlueChannel |
MagentaChannel |
YellowChannel |
BlackChannel |
OpacityChannel |
|
ClassType - The
ClassType constants specify the image storage
class.
See Image#class_type
|
UndefinedClass |
Unset value |
DirectClass |
Image is composed of
pixels which represent literal color
values. |
PseudoClass |
Image is composed of
pixels which specify an index in a color
palette. |
|
ColorspaceType - The
ColorspaceType constants are used to specify the colorspace that
quantization (color reduction and mapping) is
done under or to specify the colorspace when
encoding an output image. Colorspaces are ways of
describing colors to fit the requirements of a
particular application (e.g. Television, offset
printing, color monitors). Color reduction,
by default, takes place in the RGBColorspace.
Empirical evidence suggests that distances in
color spaces such as YUVColorspace or
YIQColorspace correspond to perceptual color
differences more closely than do distances in RGB
space. These color spaces may give better results
when color reducing an image.
When encoding an output
image, the colorspaces RGBColorspace,
CMYKColorspace, and GRAYColorspace may be
specified. The CMYKColorspace option is only
applicable when writing TIFF, JPEG, and Adobe
Photoshop bitmap (PSD) files.
See Image#colorspace
|
UndefinedColorspace |
|
RGBColorspace |
Red-Green-Blue
colorspace |
GRAYColorspace |
|
TransparentColorspace |
The Transparent color
space behaves uniquely in that it preserves the
matte channel of the image if it
exists. |
OHTAColorspace |
|
XYZColorspace |
|
YCbCrColorspace |
|
YIQColorspace |
|
YPbPrColorspace |
|
YUVColorspace |
Y-signal, U-signal, and
V-signal colorspace. YUV is most widely used to
encode color for use in television
transmission. |
CMYKColorspace |
Cyan-Magenta-Yellow-Black
colorspace. CYMK is a subtractive color system used
by printers and photographers for the rendering of
colors with ink or emulsion, normally on a white
surface. |
SRGBColorspace |
In ×Magick, this constant is named
sRGBColorspace |
|
ComplianceType - see Pixel#to_color |
SVGCompliance |
Adhere to SVG color standard. |
X11Compliance |
Adhere to X11 color standard. |
XPMCompliance |
Adhere to XPM color standard. |
AllCompliance |
The union of the 3 color standards. |
|
CompositeOperator -
The CompositeOperator constants are used to select the image composition
algorithm used to compose a composite
image with a image. By default,
each of the composite image pixels are
replaced by the corresponding image tile
pixel. Specify CompositeOperator to
select a different algorithm. |
UndefinedCompositeOp |
|
OverCompositeOp |
The result is the union of the
the two image shapes with composite
image obscuring image in the
region of overlap. |
InCompositeOp |
The result is simply
composite image cut by the shape of
image. None of the image data of
image is included in the result. |
OutCompositeOp |
The resulting image is
composite image with the shape of
image cut out. |
AtopCompositeOp |
The result is the same shape as
image, with composite image
obscuring image where the image shapes
overlap. Note that this differs from
OverCompositeOp because the portion of
composite image outside of
image's shape does not appear in the
result. |
XorCompositeOp |
The result is the image data
from both composite image and
image that is outside the overlap
region. The overlap region will be blank. |
PlusCompositeOp |
The result is just the sum of
the image data. Output values are cropped to
255 (no overflow). This operation is independent of
the matte channels. |
MinusCompositeOp |
The result of composite
image - image, with overflow
cropped to zero. The matte chanel is ignored (set
to 255, full coverage). |
AddCompositeOp |
The result of composite
image + image, with overflow
wrapping around (mod 256). |
SubtractCompositeOp |
The result of composite
image - image, with underflow
wrapping around (mod 256). The add and subtract
operators can be used to perform reversable
transformations. |
DifferenceCompositeOp |
The result of
abs(composite image - image).
This is useful for comparing two very similar
images. |
MultiplyCompositeOp |
|
BumpmapCompositeOp |
The result image
shaded by composite image. |
CopyCompositeOp |
|
CopyRedCompositeOp |
|
CopyGreenCompositeOp |
|
CopyBlueCompositeOp |
|
CopyOpacityCompositeOp |
|
ClearCompositeOp |
|
DissolveCompositeOp |
|
DisplaceCompositeOp |
|
ModulateCompositeOp |
|
ThresholdCompositeOp |
|
NoCompositeOp |
|
DarkenCompositeOp |
|
LightenCompositeOp |
|
HueCompositeOp |
|
SaturateCompositeOp |
|
ColorizeCompositeOp |
|
LuminizeCompositeOp |
|
ScreenCompositeOp |
|
OverlayCompositeOp |
|
|
CompressionType -
The CompressionType constants are used to express the desired compression
type when encoding an image. Be aware that most
image types only support a sub-set of the
available compression types. If the compression
type specified is incompatable with the image,
×Magick selects a compression type
compatable with the image type.
See Image#compression.
|
UndefinedCompression |
|
NoCompression |
|
BZipCompression |
BZip (Burrows-Wheeler
block-sorting text compression algorithm and
Huffman coding) as used by bzip2
utilities |
FaxCompression |
CCITT Group 3 FAX
compression |
Group4Compression |
CCITT Group 4 FAX compression
(used only for TIFF) |
JPEGCompression |
|
LosslessJPEGCompression |
This compression format is almost never
used. |
LZWCompression |
Lempel-Ziv-Welch (LZW)
compression (caution, patented by Unisys) |
RunlengthEncodedCompression |
|
ZipCompression |
Lempel-Ziv compression (LZ77)
as used in PKZIP and GNU gzip. |
|
DecorationType - The
DecorationType constants can be used with the decorate= method
in the Draw class to specify the text decoration
for the annotate method. |
NoDecoration |
|
UnderlineDecoration |
Underline the text. |
OverlineDecoration |
Overline the text. |
LineThroughDecoration |
Draw a horizontal line through the middle of
the text. |
|
|
FilterType - The
FilterType constants are used to adjust the filter algorithm
used when resizing images. Different filters
experience varying degrees of success with
various images and can take sigificantly
different amounts of processing time.
×Magick uses the LanczosFilter by default
since this filter has been shown to provide the
best results for most images in a reasonable
amount of time. Other filter types (e.g.
TriangleFilter) may execute much faster but may
show artifacts when the image is re-sized or
around diagonal lines. The only way to be sure is
to test the filter with sample images.
See Image#resize.
|
UndefinedFilter |
PointFilter |
BoxFilter |
TriangleFilter |
HermiteFilter |
HanningFilter |
HammingFilter |
BlackmanFilter |
GaussianFilter |
QuadraticFilter |
CubicFilter |
CatromFilter |
MitchellFilter |
LanczosFilter |
BesselFilter |
SincFilter |
|
GravityType -
The GravityType constants specify positioning of an object (e.g. text,
image) within a bounding region (e.g. an image).
Gravity provides a convenient way to locate
objects irrespective of the size of the bounding
region, in other words, you don't need to provide
absolute coordinates in order to position an
object. A common default for gravity is
NorthWestGravity.
See Draw#annotate and
Image#composite.
|
ForgetGravity |
Don't use gravity. |
NorthWestGravity |
Position object at top-left of
region |
NorthGravity |
Postiion object at top-center
of region |
NorthEastGravity |
Position object at top-right of
region |
WestGravity |
Position object at left-center
of region |
CenterGravity |
Position object at center of
region |
EastGravity |
Position object at right-center
of region |
SouthWestGravity |
Position object at left-bottom
of region |
SouthGravity |
Position object at
bottom-center of region |
SouthEastGravity |
Position object at bottom-right
of region |
|
ImageType - The
ImageType constants indicate the type classification of the
image.
See Image#image_type
and Image::Info#image_type
|
UndefinedType |
|
BilevelType |
Monochrome image |
GrayscaleType |
Grayscale image |
PaletteType |
Indexed color (palette)
image |
PaletteMatteType |
Indexed color (palette) image
with opacity |
TrueColorType |
Truecolor image |
TrueColorMatteTypeType |
Truecolor image with
opacity |
ColorSeparationType |
Cyan/Yellow/Magenta/Black
(CYMK) image |
ColorSeparationMatteType |
|
OptimizeType |
|
|
InterlaceType
- The InterlaceType constants specify the ordering of the red, green,
and blue pixel information in the image.
Interlacing is usually used to make image
information available to the user faster by
taking advantage of the space vs time tradeoff.
For example, interlacing allows images on the Web
to be recognizable sooner and satellite images to
accumulate/render with image resolution
increasing over time.
Use LineInterlace or
PlaneInterlace to create an interlaced
GIF or progressive JPEG image.
See Image#interlace.
|
UndefinedInterlace |
|
NoInterlace |
Don't interlace image
(RGBRGBRGBRGBRGBRGB...) |
LineInterlace |
Use scanline interlacing
(RRR...GGG...BBB...RRR...GGG...BBB...) |
PlaneInterlace |
Use plane interlacing
(RRRRRR...GGGGGG...BBBBBB...) |
PartitionInterlace |
Similar to plane interlacing
except that the different planes are saved to
individual files (e.g. image.R, image.G, and
image.B) |
|
NoiseType - The
NoiseType constants select
the type of noise to be added to the
image.
See Image#add_noise.
|
UniformNoise |
GaussianNoise |
MultiplicativeGaussianNoise |
ImpulseNoise |
LaplacianNoise |
PoissonNoise |
|
Opacity - The Opacity
constants represent the maximum and minimum levels
of opacity. You can specify a partial level of
opacity by choosing a number between OpaqueOpacity
and TransparentOpacity. For example, 25% opacity is
abs(Magick::TransparentOpacity-Magick::OpaqueOpacity)
* 0.25 |
TransparentOpacity |
The minimum amount of opacity. |
OpaqueOpacity |
The maximum amount of opacity. |
|
PaintMethod -
The PaintMethod constants specify how pixel colors are to be
replaced in the image.
See Image#matte_floodfill
and Image#texture_floodfill.
|
PointMethod |
Replace pixel color at
point. |
ReplaceMethod |
Replace color for all image
pixels matching color at point. |
FloodfillMethod |
Replace color for pixels
surrounding point until encountering pixel that
fails to match color at point. |
FillToBorderMethod |
Replace color for pixels
surrounding point until encountering pixels
matching border color. |
ResetMethod |
Replace colors for all
pixels in image with fill color. |
|
RenderingIntent -
Rendering intent is a
concept defined by ICC Spec ICC.1:1998-09, "File
Format for Color Profiles". ×Magick uses
RenderingIntent in order to support ICC Color
Profiles.
From the specification:
"Rendering intent specifies the style of
reproduction to be used during the evaluation of
this profile in a sequence of profiles. It
applies specifically to that profile in the
sequence and not to the entire sequence.
Typically, the user or application will set the
rendering intent dynamically at runtime or
embedding time."
See Image#rendering_intent.
|
UndefinedIntent |
|
SaturationIntent |
A rendering intent that
specifies the saturation of the pixels in the image
is preserved perhaps at the expense of accuracy in
hue and lightness. |
PerceptualIntent |
A rendering intent that
specifies the full gamut of the image is compressed
or expanded to fill the gamut of the destination
device. Gray balance is preserved but colorimetric
accuracy might not be preserved. |
AbsoluteIntent |
Absolute colorimetric |
RelativeIntent |
Relative colorimetric |
|
ResolutionType -
By default, ×Magick
defines resolutions in pixels per inch.
ResolutionType provides a means to adjust
this.
See Image#units.
|
UndefinedResolution |
|
PixelsPerInchResolution |
Density specifications are
specified in units of pixels per inch (english
units). |
PixelsPerCentimeterResolution |
Density specifications are
specified in units of pixels per centimeter (metric
units). |
|
StretchType - See Draw#font_stretch,
Draw#font_stretch=. |
NormalStretch |
UltraCondensedStretch |
ExtraCondensedStretch |
CondensedStretch |
SemiCondensedStretch |
SemiExpandedStretch |
ExpandedStretch |
ExtraExpandedStretch |
UltraExpandedStretch |
AnyStretch |
|
|
WeightType - The font
weight can be specified as one of 100, 200, 300,
400, 500, 600, 700, 800, or 900, or one of the
following constants. See Draw#font_weight,
Draw#font_weight=. |
AnyWeight |
|
NormalWeight |
Equivalent to 400 |
BoldWeight |
Equivalent to 700 |
BolderWeight |
Increases weight by 100 |
LighterWeight |
Decreases weight by 100 |
|