RMagick 2.13.1: class Image (attribute methods)

###### RMagick 2.13.1 User's Guide and Reference

# class Image < Object (attribute methods)
mixes in Comparable

## attribute methods

### background_color

img.background_color -> string
img.background_color = string or pixel

#### Description

The image's background color. By default the background color is "white".

#### Argument

Either a color name or a Pixel object.

#### Returns

A color name.

### base_columns

img.base_columns -> integer

#### Description

The number of columns in the image before any transformations. Get-only.

### base_filename

img.base_filename -> string

#### Description

The image's original filename before any transformations. Get-only.

### base_rows

img.base_rows -> integer

#### Description

The number of rows in the image before any transformations. Get-only.

### bias

img.bias -> float
img.bias = float
img.bias = string

#### Description

Add bias when convolving an image

#### Argument

Either a number between 0.0 and 1.0 or a string in the form "NN%".

### black_point_compensation

img.black_point_compensation -> `true` or `false`
img.black_point_compensation = `true` or `false` -> self

#### Description

Use black point compensation. Typically used in CMYK-to-RGB conversion along with `image.` rendering_intent=Magick::RelativeIntent

### blur

img.blur -> float
img.blur = float

#### Description

The blur factor to use when resizing. See resize.

#### Argument

> 1.0 is blurry, < 1.0 is sharp.

### border_color

img.border_color -> string
img.border_color = string or pixel

#### Description

The image's border color. The default border color is "#dfdfdf" (gray).

#### Argument

Either a color name or a Pixel object.

#### Returns

A color name.

### chromaticity

img.chromaticity -> chromaticity
img.chromaticity = chromaticity

#### Description

The red, green, blue, and white-point chromaticity values..

#### Argument

A Chromaticity object.

#### Returns

A Chromaticity object.

### class_type

img.class_type -> storage_class
img.class_type = storage_class

#### Description

The image's storage class. If DirectClass then the pixels contain valid RGB or CMYK colors. If PseudoClass then the image has a colormap referenced by the pixel's index member.

#### Argument

A ClassType constant.

#### Returns

A ClassType constant.

### color_profile

img.color_profile -> string
img.color_profile = string

#### Description

The ICC color profile.

#### Argument

A color profile is represented as a string. If the argument is `nil` instead of string then any ICC color profile present in the image is deleted.

The setter form of this attribute deletes any existing ICC color profile(s) before adding the new one. If you need to add both source and destination profiles use add_profile or profile!.

#### Returns

The current color profile, or `nil` if there is no profile.

#### See also

add_profile, delete_profile, each_profile, profile!

### colors

img.colors -> integer

#### Description

The number of colors in the colormap. Only meaningful for PseudoClass images. Get-only.

### colorspace

img.colorspace -> colorspace
img.colorspace = colorspace

#### Description

Image pixel interpretation. If the colorspace is RGBColorspace the pixels are red, green, blue. If matte is true, then red, green, blue, and opacity. If it is CMYKColorspace, the pixels are cyan, yellow, magenta, black. Otherwise the colorspace is ignored.

#### Argument

A ColorspaceType constant.

#### Returns

A ColorspaceType constant.

### columns

img.columns -> integer

#### Description

The width of the image in pixels. Get-only.

### compose

img.compose -> operator
img.compose = operator

#### Description

The image composite operator. The default is OverCompositeOp. See montage.

#### Argument

A composite operator constant.

#### Returns

A composite operator constant.

### compression

img.compression -> type
img.compression = type

#### Description

The image compression type. The default is the compression type of the specified image file.

#### Argument

A CompressionType constant.

#### Returns

A CompressionType constant.

### delay

img.delay -> integer
img.delay = integer

#### Description

Number of ticks which must expire before displaying the next image in an animated sequence. The default number of ticks is 0. By default there are 100 ticks per second but this number can be changed via the ticks_per_second attribute.

#### Argument

An integer value between 0 and 65535, inclusive.

#### Returns

The current delay value.

### density

img.density -> string
img.density = string or geometry

#### Description

The vertical and horizontal resolution in pixels of the image. The default is "72x72".

#### Argument

The density may be expressed either as a string or a Geometry object. If a string, it is in the form "XxY", or simply "X". If "Y" is omitted it is set to "X". To specify the density with a Geometry object, set the `width` attribute to the x resolution and the `height` argument to the y resolution. If `height` is nil, `width` will be used as the y resolution as well.

#### Returns

The image density represented as a string.

#### See also

Also see x_resolution and y_resolution.

### depth

img.depth -> integer

#### Description

The image depth (8, 16, or 32). Get-only.

### directory

img.directory -> string

#### Description

Tile names from within an image montage. Only valid after calling montage or reading a MIFF file which contains a directory. Get-only.

#### Returns

A newline ("\n")-delimited list of the images in the montage.

### dispose

img.dispose -> method
img.dispose = method

#### Description

GIF disposal method. This attribute is used to control how successive images are rendered (how the preceding image is disposed of) when creating a GIF animation.

#### Argument

An integer corresponding to the disposal method.

#### Returns

A DisposeType constant.

### extract_info

img.extract_info -> rectangle
img.extract_info = rectangle

#### Description

Specify a rectangle within an image, or retrieve the rectangle specified when the image was constituted. See extract=.

#### Argument

A Rectangle object.

#### Returns

A Rectangle object.

### filename

img.filename -> string

#### Description

The image filename. Get-only.

### filesize

img.filesize -> integer

#### Description

The image filesize in bytes. Get-only.

### filter

img.filter -> type
img.filter = type

#### Description

Filter to use when resizing image. The reduction filter employed has a significant effect on the time required to resize an image and the resulting quality. The default filter is Lanczos which has been shown to produce high quality results when reducing most images.

#### Argument

A FilterTypes constant.

#### Returns

A FilterTypes constant.

### format

img.format -> string
img.format = string

#### Description

The image encoding format. For example, "GIF" or "PNG". See formats.

#### Argument

The format name.

#### Returns

The format name.

### fuzz

img.fuzz -> float
img.fuzz = integer or string

#### Description

Colors within this distance are considered equal. A number of algorithms search for a target color. By default the color must be exact. Use this [attribute] to match colors that are close to the target color in RGB space.

See opaque, texture_floodfill, and transparent.

#### Argument

The argument may be a floating-point numeric value or a string in the form "NN%". In the second case, the argument is computed as a percentage of QuantumRange. For example, a value of '5%' sets `fuzz` to 0.05*QuantumRange.

#### Returns

A `Float`

### gamma

img.gamma -> float
image.gamma = float

#### Description

Gamma level of the image. The same color image displayed on two different workstations may look different due to differences in the display monitor. Use gamma correction to adjust for this color difference.

### geometry

img.geometry -> string
img.geometry = string or geometry

#### Description

Preferred size of the image when encoding.

#### Argument

A geometry string or a Geometry object.

#### Returns

A geometry string.

### gravity

img.gravity -> gravity
img.gravity = gravity

#### Description

Used with the ImageList#composite_layers method. The direction that the image gravitates within the composite.

#### Argument

A GravityType value.

#### Returns

A GravityType value.

### image_type

img.image_type -> type
img.image_type = type

#### Description

The image type classification. For example, GrayscaleType. Don't confuse this attribute with the format, that is "GIF" or "JPG". Get-only.

#### Argument

An ImageType value.

#### Returns

An ImageType value.

### interlace

img.interlace -> type
img.interlace = type

#### Description

The type of interlacing scheme (default NoInterlace). This option is used to specify the type of interlacing scheme for raw image formats such as RGB or YUV. NoInterlace means do not interlace, LineInterlace uses scanline interlacing, and PlaneInterlace uses plane interlacing. PartitionInterlace is like PlaneInterlace except the different planes are saved to individual files (e.g. image.R, image.G, and image.B). Use LineInterlace or PlaneInterlace to create an interlaced GIF or progressive JPEG image.

#### Argument

An InterlaceType constant.

#### Returns

An InterlaceType constant.

### iptc_profile

img.iptc_profile -> string
img.iptc_profile = string

#### Description

The International Press Telecommunications Council profile.

#### Argument

A IPTC profile is represented as a string. If the argument is `nil` instead of string then any IPTC profile present in the image is deleted.

#### Returns

The current IPTC profile, or `nil` if there is no profile.

#### See also

add_profile, delete_profile, each_profile. profile!

### matte

img.matte -> `true` or `false`
img.matte = `true` or `false`

#### Description

If `true`, honor the opacity values in the image pixels. See Pixel.

This attribute is deprecated in ImageMagick 6.3.5 and later. Use alpha instead.

### mean_error_per_pixel

img.mean_error_per_pixel -> float

#### Description

The mean error per pixel computed when a image is color reduced. This attribute is only valid if the `measure_error` argument to `quantize`[ImageList][Image] is set to `true`. Get-only.

### mime_type

img.mime_type -> string

#### Description

Returns the officially registered (or de facto) MIME media-type. If there is no registered media-type, returns "image/x-magick". Get-only.

### monitor

img.monitor = proc

#### Description

Establish a progress monitor. Most `Image` and `ImageList` methods will periodically call the monitor with arguments indicating the progress of the method. The argument is a Proc object that accepts the three arguments listed here:

method_name
  The name of the monitored method.
quantum
  A number between 0 and span that identifies how much of the operation has been completed (or, in some cases, remains to be completed).
span
  The number of quanta needed to complete the operation.

If the monitor proc returns `nil` or `false` the operation will be immediately terminated. To stop monitoring, set `monitor` to `nil`. Set-only.

#### Argument

Any object that can respond to

        obj.call(method_name, quantum, span)

With very large images it is possible, though not very likely, for the quantum and span arguments to be `Bignum` objects.

#### Example

    img.monitor = Proc.new do |method, offset, span|
        printf("%s is %3.0f%% complete.\n", method, (offset.to_f/span)*100)
        true
        end

    img.blur_image(0,20)

produces:

    blur_image is   0% complete.
    blur_image is   0% complete.
    blur_image is   0% complete.
    blur_image is   1% complete.
    blur_image is   2% complete.
    blur_image is   4% complete.
    blur_image is   7% complete.
    blur_image is  14% complete.
    blur_image is  28% complete.
    blur_image is  56% complete.
    blur_image is  56% complete.
    blur_image is  56% complete.
    blur_image is  56% complete.
    blur_image is  57% complete.
    blur_image is  59% complete.
    blur_image is  63% complete.
    blur_image is  70% complete.
    blur_image is  84% complete.
    blur_image is 100% complete.

#### See also

Image::Info#monitor=

### montage

img.montage -> string

#### Description

Tile size and offset within an image montage. Only valid for [images produced by montage.] The string is in the form of a geometry string. Get-only.

### normalized_mean_error

img.normalized_mean_error -> float

#### Description

The normalized mean error computed when an image is color reduced. This attribute is only valid if the `measure_error` argument to `quantize`[ImageList][Image] is set to `true`. Get-only.

### normalized_maximum_error

img.normalized_maximum_error -> float

#### Description

The normalized mean error per pixel computed when an image is color reduced. This attribute is only valid if the `measure_error` argument to `quantize`[ImageList][Image] is set to `true`. Get-only.

### number_colors

img.number_colors -> integer

#### Description

Number of unique colors in the image. Get-only.

### offset

img.offset -> integer
img.offset = integer

#### Description

Number of initial bytes to skip over when reading raw image.

### opacity

img.opacity = integer

#### Description

Attenuates the opacity channel of an image. If the image pixels are opaque, they are set to the specified opacity level. Otherwise, the pixel opacity values are blended with the supplied transparency value. Set-only.

#### Argument

A number between 0 and QuantumRange. Higher numbers increase transparency.

### orientation

img.orientation -> type
img.orientation = type

#### Description

The value of the Exif Orientation Tag.

#### Returns

An OrientationType value.

#### Notes

See http://jpegclub.org/exif_orientation.html for more information about the Exif Orientation Tag.

### page

img.page -> rectangle
img.page = rectangle

#### Description

When compositing, this attribute describes the position of this image with respect to the underlying image. See coalesce, flatten_images, and mosaic.

#### Argument

A Rectangle object.

#### Returns

A Rectangle object.

### pixel_interpolation_method

img.pixel_interpolation_method -> method
img.pixel_interpolation_method = method

#### Description

Get/set the pixel color interpolation method. Some methods (such as wave, swirl, implode, and composite) use the pixel color interpolation method to determine how to blend adjacent pixels.

#### Argument

An InterpolatePixelMethod enum value.

#### Returns

An InterpolatePixelMethod enum value.

### quality

img.quality -> integer

#### Description

For JPEG images, returns the Independent JPEG Group quality value. This number is a measurement of the amount of compression used when the image was saved. Lower numbers mean higher compression.

#### Returns

A number between 0-100.

#### Notes

For more information, see The JPEG image compression FAQ.

### quantum_depth

img.quantum_depth -> integer

#### Description

The image depth to the nearest Quantum (8, 16, or 32). Get-only.

### rendering_intent

img.rendering_intent -> type
img.rendering_intent = type

#### Description

The type of rendering intent. See http://www.cambridgeincolour.com/tutorials/color-space-conversion.htm

#### Argument

A RenderingIntent constant.

#### Returns

A RenderingIntent constant.

### rows

img.rows -> integer

#### Description

The height of the image in pixels. Get-only.

### scene

img.scene -> integer

#### Description

The scene number assigned to the image the last time the image was written to a multi-image image file. Don't confuse this attribute with `ImageList`'s scene attribute, which denotes the image to which Image methods will be sent.

### start_loop

img.start_loop -> `true` or `false`
img.start_loop = `true` or `false`

#### Description

Indicates the first image in an animation.

### ticks_per_second

img.ticks_per_second -> integer
image.ticks_per_second = integer

#### Description

Gets/sets the number of ticks per second. This attribute is used in conjunction with the delay attribute to establish the amount of time that must elapse between frames in an animation.The default is 100.

#### Returns

The current number of ticks per second

### total_colors

img.total_colors -> integer

#### Description

The number of colors in the image after quantization. Set by `quantize` [ImageList][Image] if the `measure_error` argument is `true`. Get-only.

### total_ink_density

img.total_ink_density -> float

#### Description

The total ink density for a CMYK image. Total Ink Density (TID) is determined by adding the CMYK values in the darkest shadow area in an image. Get-only.

### units

img.units -> type
img.units = type

#### Description

Units of image resolution.

#### Argument

A ResolutionType constant.

#### Returns

A ResolutionType constant.

#### See also

x_resolution, y_resolution

### virtual_pixel_method

img.virtual_pixel_method -> method
img.virtual_pixel_method = method

#### Description

Specify how "virtual pixels" behave. Virtual pixels are pixels that are outside the boundaries of the image. Methods such as blur_image, sharpen, and wave use virtual pixels.

#### Argument

The virtual pixel method can be any one of the following `VirtualPixelMethod` constants:

EdgeVirtualPixelMethod
  Extend the edge pixel toward infinity. This is the default.
MirrorVirtualPixelMethod
  Mirror the image.
TileVirtualPixelMethod
  Tile the image.
BackgroundVirtualPixelMethod
  The area surrounding the image is the background color.
TransparentVirtualPixelMethod
  The area surrounding the image is transparent blackness.
BlackVirtualPixelMethod
  The area surrounding the image is black.
GrayVirtualPixelMethod
  The area surrounding the image is gray.
WhiteVirtualPixelMethod
  The area surrounding the image is white.
RandomVirtualPixelMethod
  Choose a random pixel from the image.
DitherVirtualPixelMethod
  use a dithered pattern to choose a pixel in a 32x32 neighborhood.
HorizontalTileVirtualPixelMethod
  Horizontally tile the image
VerticalTileVirtualPixelMethod
  Vertically tile the image
HorizontalTileEdgeVirtualPixelMethod
  Horizontally tile the image and replicate the side edge pixels
VerticalTileEdgeVirtualPixelMethod
  Vertically tile the image and replicate the side edge pixels
CheckerTileVirtualPixelMethod
  Alternate squares with image and background color

Some of these values are not supported by older versions of ImageMagick. To see what values are available, enter the following code in irb:

    Magick::VirtualPixelMethod.values {|v| puts v}

#### Returns

A `VirtualPixelMethod` constant.

#### Example

      img.virtual_pixel_method = Magick::TransparentVirtualPixelMethod

### x_resolution

img.x_resolution -> float
img.x_resolution = float

#### Description

Horizontal resolution of the image.

#### See also

units

### y_resolution

img.y_resolution -> float
img.y_resolution = float

#### Description

Vertical resolution of the image.

#### See also

units