vips_black ()

intvips_black (VipsImage **out,int width,int height,...);

Optional arguments:

Make a black unsigned char image of a specified size.

See also:vips_xyz(),vips_text(),vips_gaussnoise().

vips_xyz ()

intvips_xyz (VipsImage **out,int width,int height,...);

Optional arguments:

Create a two-band uint32 image where the elements in the first band have thevalue of their x coordinate and elements in the second band have their ycoordinate.

You can make any image where the value of a pixel is a function of its (x,y) coordinate by combining this operator with the arithmetic operators.

Setcsize,dsize,esize to generate higher dimensions and add morebands. The extra dimensions are placed down the vertical axis. Usevips_grid() to change the layout.

See also:vips_grey(),vips_grid(),vips_identity().

vips_grey ()

intvips_grey (VipsImage **out,int width,int height,...);

Optional arguments:

Create a one-band float image with the left-most column zero and theright-most 1. Intermediate pixels are a linear ramp.

Setuchar to output a uchar image with the leftmost pixel 0 and therightmost 255.

See also:vips_xyz(),vips_identity().

vips_gaussmat ()

intvips_gaussmat (VipsImage **out,double sigma,double min_ampl,...);

Optional arguments:

Creates a circularly symmetric Gaussian image of radiussigma. The size of the mask is determined by the variablemin_ampl;if for instance the value .1 is entered this means that the produced maskis clipped at values less than 10 percent of the maximum amplitude.

The program uses the following equation:

H(r) = exp(-(r * r) / (2 *sigma *sigma))

The generated image has odd size and its maximum value is normalised to1.0, unlessprecision isVIPS_PRECISION_INTEGER.

Ifseparable is set, only the centre horizontal is generated. This isuseful for separable convolutions.

Ifprecision isVIPS_PRECISION_INTEGER, an integer gaussian is generated.This is useful for integer convolutions.

"scale" is set to the sum of all the mask elements.

See also:vips_logmat(),vips_conv().

vips_logmat ()

intvips_logmat (VipsImage **out,double sigma,double min_ampl,...);

Optional arguments:

Creates a circularly symmetric Laplacian of Gaussian maskof radiussigma. The size of the mask is determined by the variablemin_ampl;if for instance the value .1 is entered this means that the produced maskis clipped at values within 10 percent of zero, and where the changebetween mask elements is less than 10%.

The program uses the following equation: (from Handbook of PatternRecognition and image processing by Young and Fu, AP 1986 pages 220-221):

H(r) = (1 / (2 * M_PI * s4)) *(2 - (r2 / s2)) *exp(-r2 / (2 * s2))

where s2 =sigma *sigma, s4 = s2 * s2, r2 = r * r.

The generated mask has odd size and its maximum value is normalised to1.0, unlessprecision isVIPS_PRECISION_INTEGER.

Ifseparable is set, only the centre horizontal is generated. This isuseful for separable convolutions.

Ifprecision isVIPS_PRECISION_INTEGER, an integer mask is generated.This is useful for integer convolutions.

"scale" is set to the sum of all the mask elements.

See also:vips_gaussmat(),vips_conv().

vips_text ()

intvips_text (VipsImage **out,constchar *text,...);

Optional arguments:

Draw the stringtext to an image.out is normally a one-band 8-bitunsigned char image, with 0 for no text and 255 for text. Values betweenare used for anti-aliasing.

Setrgba to enable RGBA output. This is useful for colour emoji rendering,or support for pango markup features like<spanforeground="red">Red!</span>.

text is the text to render as a UTF-8 string. It can contain Pango markup,for example<i>The</i>Guardian.

font is the font to render with, as a fontconfig name. Examples might besans 12 or perhapsbitstream charter bold 10.

You can specify a font to load withfontfile. You'll need to also set thename of the font withfont.

width is the number of pixels to word-wrap at. By default, lines of textwider than this will be broken at word boundaries.Usewrap to set lines to wrap on word or character boundaries, or todisable line breaks.

Setjustify to turn on line justification.align can be used to set the alignment style for multi-linetext to the low (left) edge centre, or high (right) edge. Note that theoutput image can be wider thanwidth if there are noword breaks, or narrower if the lines don't break exactly atwidth.

height is the maximum number of pixels high the generated text can be. Thisonly takes effect whendpi is not set, andwidth is set, making a box.In this case,vips_text() will search for adpi and set of line breakswhich will just fit the text intowidth andheight.

You can useautofit_dpi to read out the DPI selected by auto fit.

dpi sets the resolution to render at. "sans 12" at 72 dpi draws charactersapproximately 12 pixels high.

spacing sets the line spacing, in points. It would typically be somethinglike font size times 1.2.

You can read the coordinate of the top edge of the character fromXoffset/Yoffset. This can be helpful if you need to line up the output ofseveralvips_text().

See also:vips_bandjoin(),vips_composite().

vips_gaussnoise ()

intvips_gaussnoise (VipsImage **out,int width,int height,...);

Optional arguments:

Make a one band float image of gaussian noise with the specifieddistribution. The noise distribution is created by averaging 12 randomnumbers with the appropriate weights.

See also:vips_black(),vips_xyz(),vips_text().

vips_eye ()

intvips_eye (VipsImage **out,int width,int height,...);

Optional arguments:

Create a test pattern with increasing spatial frequency in X andamplitude in Y.factor should be between 0 and 1 and determines themaximum spatial frequency.

Setuchar to output a uchar image.

See also:vips_zone().

vips_sines ()

intvips_sines (VipsImage **out,int width,int height,...);

Optional arguments:

Creates a float one band image of the a sine waveform in twodimensions.

The number of horizontal and vertical spatial frequencies aredetermined by the variableshfreq andvfreq respectively. Thefunction is useful for creating displayable sine waves andsquare waves in two dimensions.

If horfreq and verfreq are integers the resultant image is periodicaland therefore the Fourier transform does not present spikes

Pixels are normally in [-1, +1], setuchar to output [0, 255].

See also:vips_grey(),vips_xyz().

vips_zone ()

intvips_zone (VipsImage **out,int width,int height,...);

Optional arguments:

Create a one-band image of a zone plate.

Pixels are normally in [-1, +1], setuchar to output [0, 255].

See also:vips_eye(),vips_xyz().

vips_sdf ()

intvips_sdf (VipsImage **out,int width,int height,VipsSdfShape shape,...);

Optional arguments:

Create a signed distance field (SDF) image of the given shape. Differentshapes use different combinations of the optional arguments, see below.

shapeVIPS_SDF_SHAPE_CIRCLE: create a circle centred ona, radiusr.

shapeVIPS_SDF_SHAPE_BOX: create a box with top-left cornera andbottom-right cornerb.

shapeVIPS_SDF_SHAPE_ROUNDED_BOX: create a box with top-left corneraand bottom-right cornerb, whose four corners arerounded by the four-element float arraycorners.corners will default to0.0.

shapeVIPS_SDF_SHAPE_LINE: draw a line froma tob.

See also:vips_grey(),vips_grid(),vips_xyz().

vips_identity ()

intvips_identity (VipsImage **out,...);

Optional arguments:

Creates an identity lookup table, ie. one which will leave an imageunchanged when applied withvips_maplut(). Each entry in the table has avalue equal to its position.

Use the arithmetic operations on these tables to make LUTs representingarbitrary functions.

Normally LUTs are 8-bit. Setushort to create a 16-bit table.

Normally 16-bit tables have 65536 entries. You can set this smaller withsize.

See also:vips_xyz(),vips_maplut().

vips_buildlut ()

intvips_buildlut (VipsImage *in,VipsImage **out,...);

This operation builds a lookup table from a set of points. Intermediatevalues are generated by piecewise linear interpolation. The lookup table isalways of typeVIPS_FORMAT_DOUBLE, usevips_cast() to change it to thetype you need.

For example, consider this 2 x 2 matrix of (x, y) coordinates:

We then generate a 1 x 256 element LUT like this:

This is then written as the output image, with the left column giving theindex in the image to place the value.

The (x, y) points don't need to be sorted: we do that. You can haveseveral Ys, each becomes a band in the output LUT. You don't need tostart at zero, any integer will do, including negatives.

See also:vips_identity(),vips_invertlut(),vips_cast(),vips_maplut().

[method]

vips_invertlut ()

intvips_invertlut (VipsImage *in,VipsImage **out,...);

Optional arguments:

Given a mask of target values and real values, generate a LUT whichwill map reals to targets. Handy for linearising images frommeasurements of a colour chart. All values in [0,1]. Piecewise linearinterpolation, extrapolate head and tail to 0 and 1.

Eg. input like this:

Means a patch with 10% reflectance produces an image with 20% inchannel 1, 30% in channel 2, and 10% in channel 3, and so on.

Inputs don't need to be sorted (we do that). Generate any precisionLUT, default to 256 elements.

It won't work too well for non-monotonic camera responses(we should fix this). Interpolation is simple piecewise linear; we ought todo something better really.

See also:vips_buildlut().

[method]

vips_tonelut ()

intvips_tonelut (VipsImage **out,...);

Optional arguments:

vips_tonelut() generates a tone curve for the adjustment of imagelevels. It is mostly designed for adjusting the L* part of a LAB image ina way suitable for print work, but you can use it for other things too.

The curve is an unsigned 16-bit image with (in_max + 1) entries,each in the range [0,out_max].

Lb,Lw are expressed as 0-100, as in LAB colour space. Youspecify the scaling for the input and output images with thein_max andout_max parameters.

vips_mask_ideal ()

intvips_mask_ideal (VipsImage **out,int width,int height,double frequency_cutoff,...);

Optional arguments:

Make an ideal high- or low-pass filter, that is, one with a sharp cutoffpositioned atfrequency_cutoff, wherefrequency_cutoff is inthe range 0 - 1.

This operation creates a one-band float image of the specified size.The image hasvalues in the range [0, 1] and is typically used for multiplying againstfrequency domain images to filter them.Masks are created with the DC component at (0, 0). The DC pixel alwayshas the value 1.0.

Setnodc to not set the DC pixel.

Setoptical to position the DC component in the centre of the image. Thismakes the mask suitable for multiplying against optical Fourier transforms.Seevips_wrap().

Setreject to invert the sense ofthe filter. For example, low-pass becomes low-reject.

Setuchar to output an 8-bit unsigned char image rather than afloat image. In this case, pixels are in the range [0 - 255].

See also:vips_mask_ideal(),vips_mask_ideal_ring(),vips_mask_ideal_band(),vips_mask_butterworth(),vips_mask_butterworth_ring(),vips_mask_butterworth_band(),vips_mask_gaussian(),vips_mask_gaussian_ring(),vips_mask_gaussian_band().

vips_mask_ideal_ring ()

intvips_mask_ideal_ring (VipsImage **out,int width,int height,double frequency_cutoff,double ringwidth,...);

Optional arguments:

Make an ideal ring-pass or ring-reject filter, that is, one with a sharpring positioned atfrequency_cutoff of widthwidth, wherefrequency_cutoff andwidth are expressed as the range 0 - 1.

See also:vips_mask_ideal().

vips_mask_ideal_band ()

intvips_mask_ideal_band (VipsImage **out,int width,int height,double frequency_cutoff_x,double frequency_cutoff_y,double radius,...);

Optional arguments:

Make an ideal band-pass or band-reject filter, that is, one with asharp cutoff around the pointfrequency_cutoff_x,frequency_cutoff_y,of sizeradius.

See also:vips_mask_ideal().

vips_mask_butterworth ()

intvips_mask_butterworth (VipsImage **out,int width,int height,double order,double frequency_cutoff,double amplitude_cutoff,...);

Optional arguments:

Make an butterworth high- or low-pass filter, that is, one with a variable,smooth transitionpositioned atfrequency_cutoff, wherefrequency_cutoff is inrange 0 - 1. The shape of the curve is controlled byorder --- higher values give a sharper transition. See Gonzalez and Wintz,Digital Image Processing, 1987.

See also:vips_mask_ideal().

vips_mask_butterworth_ring ()

intvips_mask_butterworth_ring (VipsImage **out,int width,int height,double order,double frequency_cutoff,double amplitude_cutoff,double ringwidth,...);

Optional arguments:

Make a butterworth ring-pass or ring-reject filter, that is, one with avariable,smooth transitionpositioned atfrequency_cutoff of widthwidth, wherefrequency_cutoff isin the range 0 - 1. The shape of the curve is controlled byorder --- higher values give a sharper transition. See Gonzalez and Wintz,Digital Image Processing, 1987.

See also:vips_mask_ideal().

vips_mask_butterworth_band ()

intvips_mask_butterworth_band (VipsImage **out,int width,int height,double order,double frequency_cutoff_x,double frequency_cutoff_y,double radius,double amplitude_cutoff,...);

Optional arguments:

Make an butterworth band-pass or band-reject filter, that is, one with avariable, smooth transition positioned atfrequency_cutoff_x,frequency_cutoff_y, of radiusradius.The shape of the curve is controlled byorder --- higher values give a sharper transition. See Gonzalez and Wintz,Digital Image Processing, 1987.

See also:vips_mask_ideal().

vips_mask_gaussian ()

intvips_mask_gaussian (VipsImage **out,int width,int height,double frequency_cutoff,double amplitude_cutoff,...);

Optional arguments:

Make a gaussian high- or low-pass filter, that is, one with a variable,smooth transition positioned atfrequency_cutoff.

See also:vips_mask_ideal().

vips_mask_gaussian_ring ()

intvips_mask_gaussian_ring (VipsImage **out,int width,int height,double frequency_cutoff,double amplitude_cutoff,double ringwidth,...);

Optional arguments:

Make a gaussian ring-pass or ring-reject filter, that is, one with avariable, smooth transition positioned atfrequency_cutoff of widthringwidth.

See also:vips_mask_ideal().

vips_mask_gaussian_band ()

intvips_mask_gaussian_band (VipsImage **out,int width,int height,double frequency_cutoff_x,double frequency_cutoff_y,double radius,double amplitude_cutoff,...);

Optional arguments:

Make a gaussian band-pass or band-reject filter, that is, one with avariable, smooth transition positioned atfrequency_cutoff_x,frequency_cutoff_y, of radiusradius.

See also:vips_mask_ideal().

vips_mask_fractal ()

intvips_mask_fractal (VipsImage **out,int width,int height,double fractal_dimension,...);

Optional arguments:

This operation should be used to create fractal images by filtering thepower spectrum of Gaussian white noise. Seevips_gaussnoise().

See also:vips_mask_ideal().

vips_fractsurf ()

intvips_fractsurf (VipsImage **out,int width,int height,double fractal_dimension,...);

Generate an image of sizewidth byheight and fractal dimensionfractal_dimension. The dimension should be between 2 and 3.

See also:vips_gaussnoise(),vips_mask_fractal().

vips_worley ()

intvips_worley (VipsImage **out,int width,int height,...);

Optional arguments:

Create a one-band float image of Worley noise. See:

https://en.wikipedia.org/wiki/Worley_noise

Usecell_size to set the size of the cells from which the image isconstructed. The default is 256 x 256.

Ifwidth andheight are multiples ofcell_size, the image will tessellate.

See also:vips_perlin(),vips_fractsurf(),vips_gaussnoise().

vips_perlin ()

intvips_perlin (VipsImage **out,int width,int height,...);

Optional arguments:

Create a one-band float image of Perlin noise. See:

https://en.wikipedia.org/wiki/Perlin_noise

Usecell_size to set the size of the cells from which the image isconstructed. The default is 256 x 256.

Ifwidth andheight are multiples ofcell_size, the image will tessellate.

Normally, output pixels areVIPS_FORMAT_FLOAT in the range [-1, +1]. Setuchar to output a uchar image with pixels in [0, 255].

See also:vips_worley(),vips_fractsurf(),vips_gaussnoise().

enum VipsTextWrap

Sets the word wrapping style forvips_text() when used with a maximumwidth.

See also:vips_text().

enum VipsSdfShape

The SDF to generate,

See also:vips_sdf().