Resize

resize.Bilinear(clip clip[, int width, int height, int format, enum matrix, enum transfer, enum primaries, enum range, enum chromaloc, enum matrix_in, enum transfer_in, enum primaries_in, enum range_in, enum chromaloc_in, float filter_param_a, float filter_param_b, string resample_filter_uv, float filter_param_a_uv, float filter_param_b_uv, string dither_type, string cpu_type, bint prefer_props, float src_left, float src_top, float src_width, float src_height, float nominal_luminance])
resize.Bicubic(clip clip[, ...])
resize.Point(clip clip[, ...])
resize.Lanczos(clip clip[, ...])
resize.Spline16(clip clip[, ...])
resize.Spline36(clip clip[, ...])

In VapourSynth the resizers have several functions. In addition to scaling, they also do colorspace conversions and conversions to and from the compat formats. Resize converts a clip of known or unknown format to another clip of known or unknown format, changing only the parameters specified by the user. The resize filters can handle varying size and format input clips and turn them into constant format clips.

If you do not know which resizer to choose, then try Bicubic. It usually makes a good neutral default.

Arguments denoted as type enum may be specified by numerical index (see ITU-T H.265 Annex E.3) or by name. Enums specified by name have their argument name suffixed with “_s”. For example, a destination matrix of BT 709 can be specified either with matrix=1 or with matrix_s="709".

Note that matrix is not an optional argument when converting to YUV. Also note that if no matrix is specified in an input YUV frame’s properties then matrix_in also needs to be set.

The function will return an error if the subsampling restrictions aren’t followed.

clip:

Accepts all kinds of input.

width, height:

Output image dimensions.

format:

Output format id.

matrix, transfer, primaries:

Output colorspace specification. If not provided, the corresponding attributes from the input clip will be selected, except for YCoCg and RGB color families, where the corresponding matrix is set by default.

range:

Output pixel range. For integer formats, this allows selection of the legal code values. Even when set, out of range values (BTB/WTW) may be generated. If the input format is of a different color family, the default range is studio/limited for YUV and full-range for RGB.

chromaloc:

Output chroma location. For subsampled formats, specifies the chroma location. If the input format is 4:4:4 or RGB and the output is subsampled, the default location is left-aligned, as per MPEG. Possible chroma locations (ITU-T H.265 Figure E.1): left, center, top_left, top, bottom_left, bottom

matrix_in, transfer_in, primaries_in, range_in, chromaloc_in:

Input colorspace/format specification. If the corresponding frame property is set to a value other than unspecified, the frame property is used instead of this parameter. Default values are set for certain color families. See the equivalent output arguments for more information. By default these override the corresponding frame properties if present, to instead give the frame properties precedence when both are present set prefer_props.

filter_param_a, filter_param_b:

Parameters for the scaler used for RGB and Y-channel. For the bicubic filter, filter_param_a/b represent the “b” and “c” parameters. For the lanczos filter, filter_param_a represents the number of taps.

resample_filter_uv:

Scaling method for UV channels. It defaults to the same as for the Y-channel. The following values can be used with resample_filter_uv: point, bilinear, bicubic, spline16, spline36, lanczos.

filter_param_a_uv, filter_param_b_uv:

Parameters for the scaler used for UV channels.

dither_type:

Dithering method. Dithering is used only for conversions resulting in an integer format. The following dithering methods are available: none, ordered, random, error_diffusion.

cpu_type:

Only used for testing.

prefer_props:

Determines whether frame properties or arguments take precedence when both are present. This option affects the matrix_in, transfer_in, primaries_in, range_in and chromaloc_in arguments and their frame property equivalents.

src_left, src_top, src_width, src_height:

Used to select the source region of the input to use. Can also be used to shift the image. Defaults to the whole image.

nominal_luminance:

Determines the physical brightness of the value 1.0. The unit is in cd/m^2.

To convert to YV12:

Bicubic(clip=clip, format=vs.YUV420P8, matrix_s="709")

To resize and convert YUV with color information frame properties to planar RGB:

Bicubic(clip=clip, width=1920, height=1080, format=vs.RGB24)

To resize and convert YUV without color information frame properties to planar RGB:

Bicubic(clip=clip, width=1920, height=1080, format=vs.RGB24, matrix_in_s="709")

The following tables list values of selected colorspace enumerations and their abbreviated names. For all possible values, see ITU-T H.265.

Matrix coefficients (ITU-T H.265 Table E.5):

rgb         Identity
            The identity matrix.
            Typically used for GBR (often referred to as RGB);
            however, may also be used for YZX (often referred to as
            XYZ);
709         KR = 0.2126; KB = 0.0722
            ITU-R Rec. BT.709-5
unspec      Unspecified
            Image characteristics are unknown or are determined by the
            application.
470bg       KR = 0.299; KB = 0.114
            ITU-R Rec. BT.470-6 System B, G (historical)
            (functionally the same as the value 6 (170m))
170m        KR = 0.299; KB = 0.114
            SMPTE 170M (2004)
            (functionally the same as the value 5 (470bg))
ycgco       YCgCo
2020ncl     KR = 0.2627; KB = 0.0593
            Rec. ITU-R BT.2020 non-constant luminance system
2020cl      KR = 0.2627; KB = 0.0593
            Rec. ITU-R BT.2020 constant luminance system

Transfer characteristics (ITU-T H.265 Table E.4):

709         V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b
            V = 4.500 * Lc for b > Lc >= 0
            Rec. ITU-R BT.709-5
            (functionally the same as the values 6 (601),
            14 (2020_10) and 15 (2020_12))
unspec      Unspecified
            Image characteristics are unknown or are determined by the
            application.
601         V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b
            V = 4.500 * Lc for b > Lc >= 0
            Rec. ITU-R BT.601-6 525 or 625
            (functionally the same as the values 1 (709),
            14 (2020_10) and 15 (2020_12))
linear      V = Lc for all values of Lc
            Linear transfer characteristics
2020_10     V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b
            V = 4.500 * Lc for b > Lc >= 0
            Rec. ITU-R BT.2020
            (functionally the same as the values 1 (709),
            6 (601) and 15 (2020_12))
2020_12     V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b
            V = 4.500 * Lc for b > Lc >= 0
            Rec. ITU-R BT.2020
            (functionally the same as the values 1 (709),
            6 (601) and 14 (2020_10))
st2084      SMPTE ST 2084 (not in table)
std-b67     ARIB std-b67 (not in table)
srgb        IEC 61966-2-1

Color primaries (ITU-T H.265 Table E.3):

709         primary x y
            green 0.300 0.600
            blue 0.150 0.060
            red 0.640 0.330
            white D65 0.3127 0.3290
            Rec. ITU-R BT.709-5
unspec      Unspecified
            Image characteristics are unknown or are determined by the
            application.
170m        primary x y
            green 0.310 0.595
            blue 0.155 0.070
            red 0.630 0.340
            white D65 0.3127 0.3290
            SMPTE 170M (2004)
            (functionally the same as the value 7 (240m))
240m        primary x y
            green 0.310 0.595
            blue 0.155 0.070
            red 0.630 0.340
            white D65 0.3127 0.3290
            SMPTE 240M (1999)
            (functionally the same as the value 6 (170m))
2020        primary x y
            green 0.170 0.797
            blue 0.131 0.046
            red 0.708 0.292
            white D65 0.3127 0.3290
            Rec. ITU-R BT.2020
st432-1     DCI-P3 (not in table)

Pixel range (ITU-T H.265 Eq E-4 to E-15):

limited     Y = Clip1Y( Round( ( 1 << ( BitDepthY - 8 ) ) *
                                      ( 219 * E'Y + 16 ) ) )
            Cb = Clip1C( Round( ( 1 << ( BitDepthC - 8 ) ) *
                                       ( 224 * E'PB + 128 ) ) )
            Cr = Clip1C( Round( ( 1 << ( BitDepthC - 8 ) ) *
                                       ( 224 * E'PR + 128 ) ) )

            R = Clip1Y( ( 1 << ( BitDepthY - 8 ) ) *
                               ( 219 * E'R + 16 ) )
            G = Clip1Y( ( 1 << ( BitDepthY - 8 ) ) *
                               ( 219 * E'G + 16 ) )
            B = Clip1Y( ( 1 << ( BitDepthY - 8 ) ) *
                               ( 219 * E'B + 16 ) )
full        Y = Clip1Y( Round( ( ( 1 << BitDepthY ) - 1 ) * E'Y ) )
            Cb = Clip1C( Round( ( ( 1 << BitDepthC ) - 1 ) * E'PB +
                                  ( 1 << ( BitDepthC - 1 ) ) ) )
            Cr = Clip1C( Round( ( ( 1 << BitDepthC ) - 1 ) * E'PR +
                                  ( 1 << ( BitDepthC - 1 ) ) ) )

            R = Clip1Y( ( ( 1 << BitDepthY ) - 1 ) * E'R )
            G = Clip1Y( ( ( 1 << BitDepthY ) - 1 ) * E'G )
            B = Clip1Y( ( ( 1 << BitDepthY ) - 1 ) * E'B )