vips_copy ()

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

Optional arguments:

Copy an image, optionally modifying the header. VIPS copies images bycopying pointers, so this operation is instant, even for very large images.

You can optionally change any or all header fields during the copy. You canmake any change which does not change the size of a pel, so for exampleyou can turn a 4-band uchar image into a 2-band ushort image, but youcannot change a 100 x 100 RGB image into a 300 x 100 mono image.

See also:vips_byteswap(),vips_bandfold(),vips_bandunfold().

[method]

vips_tilecache ()

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

Optional arguments:

This operation behaves rather likevips_copy() between imagesin andout, except that it keeps a cache of computed pixels.This cache is made of up tomax_tiles tiles (a value of -1means any number of tiles), and each tile is of sizetile_widthbytile_height pixels.

Each cache tile is made with a single call tovips_region_prepare().

When the cache fills, a tile is chosen for reuse. Ifaccess isVIPS_ACCESS_RANDOM, then the least-recently-used tile is reused. Ifaccess isVIPS_ACCESS_SEQUENTIALthe top-most tile is reused.

By default,tile_width andtile_height are 128 pixels, and the operationwill cache up to 1,000 tiles.access defaults toVIPS_ACCESS_RANDOM.

Normally, only a single thread at once is allowed to calculate tiles. Ifyou setthreaded toTRUE,vips_tilecache() will allow many threads tocalculate tiles at once, and share the cache between them.

Normally the cache is dropped when computation finishes. Setpersistent toTRUE to keep the cache between computations.

See also:vips_cache(),vips_linecache().

[method]

vips_linecache ()

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

Optional arguments:

This operation behaves rather likevips_copy() between imagesin andout, except that it keeps a cache of computed scanlines.

The number of lines cached is enough for a small amount of non-localaccess.

Each cache tile is made with a single call tovips_region_prepare().

When the cache fills, a tile is chosen for reuse. Ifaccess isVIPS_ACCESS_RANDOM, then the least-recently-used tile is reused. Ifaccess isVIPS_ACCESS_SEQUENTIAL, thenthe top-most tile is reused.access defaults toVIPS_ACCESS_RANDOM.

tile_height can be used to set the size of the strips thatvips_linecache() uses. The default is 1 (a single scanline).

Normally, only a single thread at once is allowed to calculate tiles. Ifyou setthreaded toTRUE,vips_linecache() will allow many threads tocalculate tiles at once and share the cache between them.

See also:vips_cache(),vips_tilecache().

[method]

vips_sequential ()

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

Optional arguments:

This operation behaves rather likevips_copy() between imagesin andout, except that it checks that pixels onin are only requestedtop-to-bottom. This operation is useful for loading file formats which arestrictly top-to-bottom, like PNG.

tile_height can be used to set the size of the tiles thatvips_sequential() uses. The default value is 1.

See also:vips_cache(),vips_linecache(),vips_tilecache().

[method]

vips_copy_file ()

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

A simple convenience function to copy an image to a file, then copyagain to output. If the image is already a file, just copy straightthrough.

The file is allocated withvips_image_new_temp_file().The file is automatically deleted whenout is closed.

See also:vips_copy(),vips_image_new_temp_file().

[method]

vips_embed ()

intvips_embed (VipsImage *in,VipsImage **out,int x,int y,int width,int height,...);

Optional arguments:

The opposite ofvips_extract_area(): embedin within an image of sizewidth byheight at positionx,y.

extendcontrols what appears in the new pels, seeVipsExtend.

See also:vips_extract_area(),vips_insert().

[method]

vips_gravity ()

intvips_gravity (VipsImage *in,VipsImage **out,VipsCompassDirection direction,int width,int height,...);

Optional arguments:

The opposite ofvips_extract_area(): placein within an image of sizewidth byheight at a certain gravity.

extendcontrols what appears in the new pels, seeVipsExtend.

See also:vips_extract_area(),vips_insert().

vips_flip ()

intvips_flip (VipsImage *in,VipsImage **out,VipsDirection direction,...);

Flips an image left-right or up-down.

See also:vips_rot().

[method]

vips_insert ()

intvips_insert (VipsImage *main,VipsImage *sub,VipsImage **out,int x,int y,...);

Optional arguments:

Insertsub intomain at positionx,y.

Normallyout shows the whole ofmain. Ifexpand isTRUE thenout ismade large enough to hold all ofmain andsub.Any areas ofout not coming fromeithermain orsub are set tobackground (default 0).

Ifsub overlapsmain,sub will appear on top ofmain.

If the number of bands differs, one of the imagesmust have one band. In this case, an n-band image is formed from theone-band image by joining n copies of the one-band image together, and thenthe two n-band images are operated upon.

The two input images are cast up to the smallest common type (see tableSmallest common format in

See also:vips_join(),vips_embed(),vips_extract_area().

[method]

vips_join ()

intvips_join (VipsImage *in1,VipsImage *in2,VipsImage **out,VipsDirection direction,...);

Optional arguments:

Joinin1 andin2 together, left-right or up-down depending on the valueofdirection.

If one is taller or wider than theother,out will be has high as the smaller. Ifexpand isTRUE, thenthe output will be expanded to contain all of the input pixels.

Usealign to set the edge that the images align on. By default, they alignon the edge with the lower value coordinate.

Usebackground to set the colour of any pixels inout which are notpresent in eitherin1 orin2.

Useshim to set the spacing between the images. By default this is 0.

If the number of bands differs, one of the imagesmust have one band. In this case, an n-band image is formed from theone-band image by joining n copies of the one-band image together, and thenthe two n-band images are operated upon.

The two input images are cast up to the smallest common type (see tableSmallest common format in

If you are going to be joining many thousands of images in a regulargrid,vips_arrayjoin() is a better choice.

See also:vips_arrayjoin(),vips_insert().

vips_arrayjoin ()

intvips_arrayjoin (VipsImage **in,VipsImage **out,int n,...);

Optional arguments:

Lay out the images inin in a grid. The grid isacross images across andhowever high is necessary to use up all ofin. Images are set downleft-to-right and top-to-bottom.across defaults ton.

Each input image is placed with a box of sizehspacing byvspacingpixels and cropped. These default to the largest width and largest heightof the input images.

Space between images is filled withbackground. This defaults to 0(black).

Images are positioned within theirhspacing byvspacing box at low,centre or high coordinate values, controlled byhalign andvalign. Thesedefault to left-top.

Boxes are joined and separated byshim pixels. This defaults to 0.

If the number of bands in the input images differs, all but one of theimages must have one band. In this case, an n-band image is formed from theone-band image by joining n copies of the one-band image together, and thenthe n-band images are operated upon.

The input images are cast up to the smallest common type (see tableSmallest common format in

vips_colourspace() can be useful for moving the images to a commoncolourspace for compositing.

See also:vips_join(),vips_insert(),vips_colourspace().

vips_extract_area ()

intvips_extract_area (VipsImage *in,VipsImage **out,int left,int top,int width,int height,...);

Extract an area from an image. The area must fit withinin.

See also:vips_extract_bands(),vips_smartcrop().

[method]

vips_crop ()

intvips_crop (VipsImage *in,VipsImage **out,int left,int top,int width,int height,...);

A synonym forvips_extract_area().

See also:vips_extract_bands(),vips_smartcrop().

[method]

vips_smartcrop ()

intvips_smartcrop (VipsImage *in,VipsImage **out,int width,int height,...);

Optional arguments:

Crop an image down to a specified width and height by removing boring parts.

Useinteresting to pick the method vips uses to decide which bits of theimage should be kept.

You can test xoffset / yoffset onout to find the location of the cropwithin the input image.

See also:vips_extract_area().

[method]

vips_extract_band ()

intvips_extract_band (VipsImage *in,VipsImage **out,int band,...);

Optional arguments:

Extract a band or bands from an image. Extracting out of range is an error.

See also:vips_extract_area().

[method]

vips_replicate ()

intvips_replicate (VipsImage *in,VipsImage **out,int across,int down,...);

Repeats an image many times.

See also:vips_extract_area().

[method]

vips_grid ()

intvips_grid (VipsImage *in,VipsImage **out,int tile_height,int across,int down,...);

Chop a tall thin image up into a set of tiles, lay the tiles out in a grid.

The input image should be a very tall, thin image containing a list ofsmaller images. Volumetric or time-sequence images are often laid out likethis. This image is chopped into a series of tiles, eachtile_heightpixels high and the width ofin. The tiles are then rearranged into a gridacross tiles across anddown tiles down in row-major order.

Supplyingtile_height,across anddown is not strictly necessary, weonly really need two of these. Requiring three is a double-check that theimage has the expected geometry.

See also:vips_embed(),vips_insert(),vips_join().

[method]

vips_transpose3d ()

intvips_transpose3d (VipsImage *in,VipsImage **out,...);

Optional arguments:

Transpose a volumetric image.

Volumetric images are very tall, thin images, with the metadata itemVIPS_META_PAGE_HEIGHT set to the height of each sub-image.

This operation swaps the two major dimensions, so that page N in theoutput contains the Nth scanline, in order, from each input page.

You can override theVIPS_META_PAGE_HEIGHT metadata item with the optionalpage_height parameter.

VIPS_META_PAGE_HEIGHT in the output image is the number of pages in theinput image.

See also:vips_grid().

[method]

vips_wrap ()

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

Optional arguments:

Slice an image up and move the segments about so that the pixel that wasat 0, 0 is now atx,y. Ifx andy are not set, they default to thecentre of the image.

See also:vips_embed(),vips_replicate().

[method]

vips_rot ()

intvips_rot (VipsImage *in,VipsImage **out,VipsAngle angle,...);

Rotatein by a multiple of 90 degrees.

Usevips_similarity() to rotate by an arbitrary angle.vips_rot45() isuseful for rotating convolution masks by 45 degrees.

See also:vips_flip(),vips_similarity(),vips_rot45().

[method]

vips_rot90 ()

intvips_rot90 (VipsImage *in,VipsImage **out,...);

Rotatein by 90 degrees clockwise. A convenience function overvips_rot().

See also:vips_rot().

vips_rot180 ()

intvips_rot180 (VipsImage *in,VipsImage **out,...);

Rotatein by 180 degrees. A convenience function overvips_rot().

See also:vips_rot().

[method]

vips_rot270 ()

intvips_rot270 (VipsImage *in,VipsImage **out,...);

Rotatein by 270 degrees clockwise. A convenience function overvips_rot().

See also:vips_rot().

[method]

vips_rot45 ()

intvips_rot45 (VipsImage *in,VipsImage **out,...);

Optional arguments:

Rotatein by a multiple of 45 degrees. Odd-length sides and square imagesonly.

This operation is useful for rotating convolution masks. Usevips_similarity() to rotate images by arbitrary angles.

See also:vips_rot(),vips_similarity().

[method]

vips_autorot_remove_angle ()

voidvips_autorot_remove_angle (VipsImage *image);

Remove the orientation tag onimage. Also remove any exif orientation tags.You mustvips_copy() the image before calling this function since itmodifies metadata.

[method]

vips_autorot ()

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

Optional arguments:

Look at the image metadata and rotate and flip the image to make itupright. TheVIPS_META_ORIENTATION tag is removed fromout to preventaccidental double rotation.

Readangle to find the amount the image was rotated by. Readflip tosee if the image was also flipped.

[method]

vips_zoom ()

intvips_zoom (VipsImage *in,VipsImage **out,int xfac,int yfac,...);

Zoom an image by repeating pixels. This is fast nearest-neighbourzoom.

See also:vips_affine(),vips_subsample().

[method]

vips_subsample ()

intvips_subsample (VipsImage *in,VipsImage **out,int xfac,int yfac,...);

Optional arguments:

Subsample an image by an integer fraction. This is fast, nearest-neighbourshrink.

For small horizontal shrinks, this operation will fetch lines of pixelsfromin and then subsample that line. For large shrinks it will fetchsingle pixels.

Ifpoint is set,in will always be sampled in points. This can be fasterif the previous operations in the pipeline are very slow.

See also:vips_affine(),vips_shrink(),vips_zoom().

[method]

vips_cast ()

intvips_cast (VipsImage *in,VipsImage **out,VipsBandFormat format,...);

Optional arguments:

Convertin toformat. You can convert between any pair of formats.Floats are truncated (not rounded). Out of range values are clipped.

Casting from complex to real returns the real part.

Ifshift isTRUE, integer values are shifted up and down. For example,casting from unsigned 8 bit to unsigned 16 bit wouldshift every value left by 8 bits. The bottom bit is copied into the newbits, so 255 would become 65535.

See also:vips_scale(),vips_complexform(),vips_real(),vips_imag(),vips_cast_uchar(),vips_msb().

[method]

vips_cast_uchar ()

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

Convertin toVIPS_FORMAT_UCHAR. Seevips_cast().

[method]

vips_cast_char ()

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

Convertin toVIPS_FORMAT_CHAR. Seevips_cast().

[method]

vips_cast_ushort ()

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

Convertin toVIPS_FORMAT_USHORT. Seevips_cast().

[method]

vips_cast_short ()

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

Convertin toVIPS_FORMAT_SHORT. Seevips_cast().

[method]

vips_cast_uint ()

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

Convertin toVIPS_FORMAT_UINT. Seevips_cast().

[method]

vips_cast_int ()

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

Convertin toVIPS_FORMAT_INT. Seevips_cast().

[method]

vips_cast_float ()

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

Convertin toVIPS_FORMAT_FLOAT. Seevips_cast().

[method]

vips_cast_double ()

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

Convertin toVIPS_FORMAT_DOUBLE. Seevips_cast().

[method]

vips_cast_complex ()

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

Convertin toVIPS_FORMAT_COMPLEX. Seevips_cast().

[method]

vips_cast_dpcomplex ()

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

Convertin toVIPS_FORMAT_DPCOMPLEX. Seevips_cast().

[method]

vips_scale ()

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

Optional arguments:

Search the image for the maximum and minimum value, then return the imageas unsigned 8-bit, scaled so that the maximum value is 255 and theminimum is zero.

Iflog is set, transform with log10(1.0 + pow(x,exp)) + .5,then scale so max == 255. By default,exp is 0.25.

See also:vips_cast().

[method]

vips_msb ()

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

Optional arguments:

Turn any integer image to 8-bit unsigned char by discarding all but the mostsignificant byte. Signed values are converted to unsigned by adding 128.

Useband to make a one-band 8-bit image.

This operator also works for LABQ coding.

See also:vips_scale(),vips_cast().

[method]

vips_byteswap ()

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

Swap the byte order in an image.

See also:vips_rawload().

[method]

vips_bandjoin ()

intvips_bandjoin (VipsImage **in,VipsImage **out,int n,...);

Join a set of images together, bandwise.

If the imageshave n and m bands, then the output image will have n + mbands, with the first n coming from the first image and the last mfrom the second.

If the images differ in size, the smaller images are enlarged to match thelarger by adding zero pixels along the bottom and right.

The input images are cast up to the smallest common type (see tableSmallest common format in

See also:vips_insert().

vips_bandjoin2 ()

intvips_bandjoin2 (VipsImage *in1,VipsImage *in2,VipsImage **out,...);

Join a pair of images together, bandwise. Seevips_bandjoin().

vips_bandjoin_const ()

intvips_bandjoin_const (VipsImage *in,VipsImage **out,double *c,int n,...);

Append a set of constant bands to an image.

See also:vips_bandjoin().

[method]

vips_bandjoin_const1 ()

intvips_bandjoin_const1 (VipsImage *in,VipsImage **out,double c,...);

Append a single constant band to an image.

[method]

vips_bandrank ()

intvips_bandrank (VipsImage **in,VipsImage **out,int n,...);

Optional arguments:

Sorts the imagesin band-element-wise, then outputs animage in which each band element is selected from the sorted list by theindex parameter. For example, ifindexis zero, then each output band element will be the minimum of all thecorresponding input band elements.

By default,index is -1, meaning pick the median value.

It works for any uncoded, non-complex image type. Images are cast up to thesmallest common-format.

Any image can have either 1 band or n bands, where n is the same for allthe non-1-band images. Single band images are then effectively copied tomake n-band images.

Smaller input images are expanded by adding black pixels.

See also:vips_rank().

vips_bandfold ()

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

Optional arguments:

Fold up an image horizontally: width is collapsed into bands.Usefactor to set how much to fold by:factor 3, for example, will makethe output image three times narrower than the input, and with three timesas many bands. By default the whole of the input width is folded up.

See also:vips_csvload(),vips_bandunfold().

[method]

vips_bandunfold ()

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

Optional arguments:

Unfold image bands into x axis.Usefactor to set how much to unfold by:factor 3, for example, will makethe output image three times wider than the input, and with one thirdas many bands. By default, all bands are unfolded.

See also:vips_csvload(),vips_bandfold().

[method]

vips_bandbool ()

intvips_bandbool (VipsImage *in,VipsImage **out,VipsOperationBoolean boolean,...);

Perform various boolean operations across the bands of an image. Forexample, a three-band uchar image operated on withVIPS_OPERATION_BOOLEAN_AND will produce a one-band uchar image where eachpixel is the bitwise and of the band elements of the corresponding pixel inthe input image.

The output image is the same format as the input image for integertypes. Float types are cast to int before processing. Complex types are notsupported.

The output image always has one band.

This operation is useful in conjunction withvips_relational(). You can useit to see if all image bands match exactly.

See also:vips_boolean_const().

[method]

vips_bandand ()

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

PerformVIPS_OPERATION_BOOLEAN_AND on an image. Seevips_bandbool().

[method]

vips_bandor ()

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

PerformVIPS_OPERATION_BOOLEAN_OR on an image. Seevips_bandbool().

[method]

vips_bandeor ()

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

PerformVIPS_OPERATION_BOOLEAN_EOR on an image. Seevips_bandbool().

[method]

vips_bandmean ()

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

This operation writes a one-band image where each pixel is the average ofthe bands for that pixel in the input image. The output band format isthe same as the input band format. Integer types use round-to-nearestaveraging.

See also:vips_add(),vips_avg(),vips_recomb()

[method]

vips_recomb ()

intvips_recomb (VipsImage *in,VipsImage **out,VipsImage *m,...);

This operation recombines an image's bands. Each pixel inin is treated asan n-element vector, where n is the number of bands inin, and multiplied bythe n x m matrixm to produce the m-band imageout.

out is always float, unlessin is double, in which caseout is doubletoo. No complex images allowed.

It's useful for various sorts of colour space conversions.

See also:vips_bandmean().

[method]

vips_ifthenelse ()

intvips_ifthenelse (VipsImage *cond,VipsImage *in1,VipsImage *in2,VipsImage **out,...);

Optional arguments:

This operation scans the condition imagecondand uses it to select pixels from either the then imagein1 or the elseimagein2. Non-zero meansin1, 0 meansin2.

Any image can have either 1 band or n bands, where n is the same for allthe non-1-band images. Single band images are then effectively copied tomake n-band images.

Imagesin1 andin2 are cast up to the smallest common format.cond iscast to uchar.

If the images differ in size, the smaller images are enlarged to match thelargest by adding zero pixels along the bottom and right.

Ifblend isTRUE, then values inout are smoothly blended betweenin1andin2 using the formula:

out = (cond / 255) *in1 + (1 -cond / 255) *in2

See also:vips_equal().

vips_switch ()

intvips_switch (VipsImage **tests,VipsImage **out,int n,...);

Thetests images are evaluated and at each point the index of the firstnon-zero value is written toout. If alltests are false, the value(n + 1) is written.

Images intests must have one band. They are expanded to thebounding box of the set of images intests, and that size is used forout.tests can have up to 255 elements.

Combine withvips_case() to make an efficient multi-wayvips_ifthenelse().

See also:vips_maplut(),vips_case(),vips_ifthenelse().

vips_flatten ()

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

Optional arguments:

Take the last band ofin as an alpha and use it to blend theremaining channels withbackground.

The alpha channel is 0 -max_alpha, wheremax_alpha means 100% imageand 0 means 100% background.background defaults to zero (black).

max_alpha has the default value 255, or 65535 for images tagged asVIPS_INTERPRETATION_RGB16 orVIPS_INTERPRETATION_GREY16.

Useful for flattening PNG images to RGB.

Non-complex images only.

See also:vips_premultiply(),vips_pngload().

[method]

vips_addalpha ()

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

Append an alpha channel.

See also:vips_image_hasalpha().

[method]

vips_premultiply ()

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

Optional arguments:

Premultiplies any alpha channel.The final band is taken to be the alphaand the bands are transformed as:

123

alpha=clip(0,in[in.bands-1],@max_alpha);norm=alpha/@max_alpha;out=[in[0]*norm,...,in[in.bands-1]*norm,alpha];

So for an N-band image, the first N - 1 bands are multiplied by the clippedand normalised final band, the final band is clipped.If there is only a single band,the image is passed through unaltered.

The result isVIPS_FORMAT_FLOAT unless the input format isVIPS_FORMAT_DOUBLE, in whichcase the output is double as well.

max_alpha has the default value 255, or 65535 for images tagged asVIPS_INTERPRETATION_RGB16 orVIPS_INTERPRETATION_GREY16.

Non-complex images only.

See also:vips_unpremultiply(),vips_flatten().

[method]

vips_unpremultiply ()

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

Optional arguments:

Unpremultiplies any alpha channel.Bandalpha_band (by default the final band) contains the alpha and allother bands are transformed as:

123456

alpha=(int)clip(0,in[in.bands-1],@max_alpha);norm=(double)alpha/@max_alpha;if(alpha==0)out=[0,...,0,alpha];elseout=[in[0]/norm,...,in[in.bands-1]/norm,alpha];

So for an N-band image, the first N - 1 bands are divided by the clippedand normalised final band, the final band is clipped.If there is only a single band, the image is passed through unaltered.

The result isVIPS_FORMAT_FLOAT unless the input format isVIPS_FORMAT_DOUBLE, in whichcase the output is double as well.

max_alpha has the default value 255, or 65535 for images tagged asVIPS_INTERPRETATION_RGB16 orVIPS_INTERPRETATION_GREY16.

Non-complex images only.

See also:vips_premultiply(),vips_flatten().

[method]

vips_composite ()

intvips_composite (VipsImage **in,VipsImage **out,int n,int *mode,...);

Optional arguments:

Composite an array of images together.

Images are placed in a stack, within[0] at the bottom andin[n - 1] atthe top. Pixels are blended together working from the bottom upwards, withthe blend mode at each step being set by the correspondingVipsBlendModeinmode.

Images are transformed to a compositing space before processing. This isVIPS_INTERPRETATION_sRGB,VIPS_INTERPRETATION_B_W,VIPS_INTERPRETATION_RGB16, orVIPS_INTERPRETATION_GREY16by default, depending onhow many bands and bits the input images have. You can select any otherspace, such asVIPS_INTERPRETATION_LAB orVIPS_INTERPRETATION_scRGB.

The output image is in the compositing space. It will always beVIPS_FORMAT_FLOAT unless one of the inputs isVIPS_FORMAT_DOUBLE, inwhich case the output will be double as well.

Complex images are not supported.

The output image will always have an alpha band. A solid alpha isadded to any input missing an alpha.

The images do not need to match in size or format. The output image isalways the size ofin[0], with other images beingpositioned with thex andy parameters and clippedagainst that rectangle.

Image are normally treated as unpremultiplied, so this operation can be useddirectly on PNG images. If your images have been throughvips_premultiply(),setpremultiplied.

See also:vips_insert().

vips_composite2 ()

intvips_composite2 (VipsImage *base,VipsImage *overlay,VipsImage **out,VipsBlendMode mode,...);

Optional arguments:

Compositeoverlay on top ofbase withmode. Seevips_composite().

[method]

vips_falsecolour ()

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

Forcein to 1 band, 8-bit, then transform toa 3-band 8-bit image with a false colourmap. The map is supposed to make small differences in brightness moreobvious.

See also:vips_maplut().

[method]

vips_gamma ()

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

Optional arguments:

Calculatein ** (1 /exponent), normalising to the maximum range of theinput type. For float types use 1.0 as the maximum.

See also:vips_identity(),vips_pow_const1(),vips_maplut()

[method]

enum VipsExtend

Seevips_embed(),vips_conv(),vips_affine() and so on.

When the edges of an image are extended, you can specifyhow you want the extension done.

VIPS_EXTEND_BLACK --- new pixels are black, ie. all bits are zero.

VIPS_EXTEND_COPY --- each new pixel takes the value of the nearest edgepixel

VIPS_EXTEND_REPEAT --- the image is tiled to fill the new area

VIPS_EXTEND_MIRROR --- the image is reflected and tiled to reduce hashedges

VIPS_EXTEND_WHITE --- new pixels are white, ie. all bits are set

VIPS_EXTEND_BACKGROUND --- colour set from thebackground property

We have to specify the exact value of each enum member since we have tokeep these frozen for back compat with vips7.

See also:vips_embed().

enum VipsCompassDirection

A direction on a compass. Used forvips_gravity(), for example.

enum VipsDirection

Seevips_flip(),vips_join() and so on.

Operations likevips_flip() need to be told whether to flip left-right ortop-bottom.

See also:vips_flip(),vips_join().

enum VipsAlign

Seevips_join() and so on.

Operations likevips_join() need to be told whether to align images on thelow or high coordinate edge, or centre.

See also:vips_join().

enum VipsAngle

Seevips_rot() and so on.

Fixed rotate angles.

See also:vips_rot().

enum VipsAngle45

Seevips_rot45() and so on.

Fixed rotate angles.

See also:vips_rot45().

enum VipsInteresting

Pick the algorithm vips uses to decide image "interestingness". This is usedbyvips_smartcrop(), for example, to decide what parts of the image tokeep.

VIPS_INTERESTING_NONE andVIPS_INTERESTING_LOW mean the same -- thecrop is positioned at the top or left.VIPS_INTERESTING_HIGH positions atthe bottom or right.

See also:vips_smartcrop().

enum VipsBlendMode

The various Porter-Duff and PDF blend modes. Seevips_composite(),for example.

The Cairo docs have a nice explanation of all the blend modes:

https://www.cairographics.org/operators

The non-separable modes are not implemented.