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Article contents:== leptonic [[toc:]] === Description This egg provides a Scheme interface to the ''leptonica'' image processing library authored by Dan Bloomberg. The egg offers a subset of the extensive leptonica C-API, focusing on a set of high-level ''leptonica'' functions that are likely to be useful to Scheme programmers. === Author Jules Altfas === Repository https://codeberg.org/jrapdx/leptonic === Requirements The egg has these dependencies: * the leptonica library – https://github.com/DanBloomberg/leptonica, which is dependent on: ** libjpeg – https://sourceforge.net/projects/libjpeg-turbo/ ** libtiff – https://gitlab.com/libtiff/libtiff ** libpng – https://libpng.sourceforge.io/index.html ** libz – https://zlib.net/ ** libwebp – https://github.com/webmproject/libwebp ** libgif – https://giflib.sourceforge.net ** libopenjp2 – https://github.com/uclouvain/openjpeg The image libraries are available on many platforms through their respective package systems. Installing from source is an option if one or more are not otherwise available. === Installing On unix platforms, the egg should install normally with {{chicken-install -s leptonic}}, or alternatively, clone/download the repo and run {{chicken-install -s}} in the local directory. On Windows, the leptonica library needs to be installed ''before'' installing the egg. Make sure {{libleptonica-6.dll}} is in a directory on the exec path. Then {{chicken-install}} should compile/install the egg without errors. Programs using/importing {{leptonic}} need to be linked with the leptonica library. # Install image libraries through the system package manager or from source if not otherwise available. # Install the leptonica library. (See the leptonica site at http://www.leptonica.org/source/README.html for detailed instructions for compiling from source.) === Using the leptonic egg The leptonica library abstracts image data into one of several C-structs which are used by functions to read/write image files, perform scaling, morphing, modifying and coverting images. An advantage of this approach is the simplicity and uniformity it provides for library users. libleptonica includes a wealth of high- and low-level functions for these purposes. A selection of the library’s high-level functions are represented in this egg. The primary C-struct is “Pix” with fields including width, height, depth (1,2,4,8,32 bits/pixel), samples/pixel, xres, yres, colormap, and img-data (array of {{unsigned-int32}}). Users should regard Pix and other structures as opaque as the “internals” are handled by the procedures. Most of the Scheme procedures take/return ‘ppix’ (ptr to struct Pix) along with other arguments. A major benefit of leptonica is that image processing is decoupled from input/output format, greatly simplifying programs that handle image files. A typical usage pattern starts with reading an image file with ‘pix-read’ (or ‘pix-read-FORMAT’), returning a ppix (ptr to Pix). Manipulations are applied and finally, ‘pix-write’ or ‘pix-write-FORMAT’ writes ppix data to an output file. === Leptonic egg api ==== Format-type procedures <procedure>n->ftype N</procedure> * in - N - {{int}}, with value 0 to 19.<br /> * returns: symbol, e.g., ’IFF_JFIF_JPEG <procedure>ftype->n TYPE</procedure> * in - TYPE - {{symbol}}<br /> * returns: {{int}}. (See TABLE.) TABLE. leptonica image formats <table> <tr><th>integer</th><th>symbol</th></tr> <tr><td>0</td><td>IFF_UNKNOWN</td></tr> <tr><td>1</td><td>IFF_BMP</td></tr> <tr><td>2</td><td>IFF_JFIF_JPEG</td></tr> <tr><td>3</td><td>IFF_PNG</td></tr> <tr><td>4</td><td>IFF_TIFF</td></tr> <tr><td>5</td><td>IFF_TIFF_PACKBITS</td></tr> <tr><td>6</td><td>IFF_TIFF_RLE</td></tr> <tr><td>7</td><td>IFF_TIFF_G3</td></tr> <tr><td>8</td><td>IFF_TIFF_G4</td></tr> <tr><td>9</td><td>IFF_TIFF_LZW</td></tr> <tr><td>10</td><td>IFF_TIFF_ZIP</td></tr> <tr><td>11</td><td>IFF_PNM</td></tr> <tr><td>12</td><td>IFF_PS</td></tr> <tr><td>13</td><td>IFF_GIF</td></tr> <tr><td>14</td><td>IFF_JP2</td></tr> <tr><td>15</td><td>IFF_WEBP</td></tr> <tr><td>16</td><td>IFF_LPDF</td></tr> <tr><td>17</td><td>IFF_TIFF_JPEG</td></tr> <tr><td>18</td><td>IFF_DEFAULT</td></tr> <tr><td>19</td><td>IFF_SPIX</td></tr> </table> ==== Foreign types (define-foreign-type pix (struct Pix)) (define-foreign-type ppix (c-ptr (struct Pix))) (define-foreign-type pixa (struct Pixa)) (define-foreign-type ppixa (c-ptr (struct Pixa))) (define-foreign-type fpix (struct FPix)) ;; float pix (define-foreign-type pfpix (c-ptr (struct FPix))) (define-foreign-type fpixa (struct FPixa)) ;; array of FPix (define-foreign-type pfpixa (c-ptr (struct FPixa))) Use {{(include "leptonic-types.scm")}} to make these available. ==== Reading image files <procedure>pix-read FILENAME</procedure> * in - FILENAME * returns: ppix or #f on error. <procedure>pix-read-header FILENAME PFMT PW PH PBPS PSPP PISCMAP</procedure> * in - FILENAME - {{string}} * in - PFMT PW PH PBPS PSPP PISCMAP - {{ptr to unsigned-int32}} ** Other args are optional, pass #f to skip. ** Optionals, in order: image-format, width, height, bits/sample, samples/pixel, img has colormap?(0=no/1=yes). (import leptonic) (define-external fmt unsigned-int32) (define-external w unsigned-int32) (define-external h unsigned-int32) (define-external bps unsigned-int32) (define-external spp unsigned-int32) (define-external cmap unsigned-int32) (pix-read-header "img1.jpg" (location fmt) (location w) (location h) (location bps) (location spp) (location cmap)) ;; fmt -> 2, w -> 898, h -> 606, bps -> 8, spp -> 3, cmap -> 0 ;; image is 24bpp (bps * spp) <procedure>pix-get-width PPIX</procedure> * in - PPIX * returns: width as {{int}}. <procedure>pix-get-height PPIX</procedure> * in - PPIX * returns: height as {{int}}. <procedure>get-implied-fmt FILENAME</procedure> * in - FILENAME - {{string}} * returns: format as {{int}}. <procedure>find-file-fmt FILENAME PFMT</procedure> * in - FILENAME - {{string}} * out - PFMT - {{ptr to int}} * returns: 0 on success, 1 if error/unrecognized format. (define-external fmt int) (define r (find-file-fmt "file0.png" (location fmt))) ;; r -> 0 (no error), fmt -> 3 ==== Writing image files <procedure>pix-write FILENAME PPIX FORMAT</procedure> * in - FILENAME {{string}} * in - PPIX * in - FORMAT {{int}} * returns: 0 on success, 1 if error. <procedure>pix-write-jpeg FILENAME PPIX QUALITY PROGRESSIVE</procedure> * in - FILENAME - {{string}} * in - PPIX * in - QUALITY - {{int32}} - 1 to 100, 75 is default * in - PROGRESSIVE - {{int32}} - 1=yes, 0=no * returns: 0 on success, 1 if error. <procedure>pix-write-png FILENAME PPIX GAMMA</procedure> * in - FILENAME - {{string}} * in - PPIX * in - GAMMA - {{float}} - 0.0 if not defined * returns: 0 on success, 1 if error. <procedure>pix-write-webp FILENAME PPIX QUALITY LOSSLESS</procedure> * in - FILENAME - {{string}} * in - PPIX * in - QUALITY - {{int32}} - 1 to 100 * in - LOSSLESS - {{int32}} - 1=yes, 0=no * returns: 0 on success, 1 if error. <procedure>pix-copy PPIXD PPIX</procedure> * in - PPIXD - #f or PPIX (in-place: {{pix-copy ppix ppix}}) * in - PPIX * returns: copy of ppix ==== Deallocating image data <procedure>pix-destroy PTR-TO-PPIX</procedure> * in - PTR-TO-PPIX - {{ptr ppix}} * returns: no return value (define-external ppx ppix (pix-read "img0.jpg")) ... (pix-destroy (location ppx)) <procedure>pix-free-data PPIX</procedure> * in - PPIX ** ''(Deallocates data member but not Pix structure itself, use {{pix-destroy PPIX}} when PPIX no longer needed.)'' * returns: no return value ==== Scaling <procedure>pix-scale PPIX SCALEX SCALEY</procedure> * in - PPIX - input * in - SCALEX, SCALEY - {{float}} values. ** ''(Uses: sharpening for scale factors 0.2-0.7, ** ‘linear interpolation’ for factors 0.7-1.4, and ** no sharpening when scale factors > 1.4.)'' * returns: scaled ppix on success, #f on error. <procedure>pix-scale-general PPIX SCALEX SCALEY SHARPFRAC SHARPWIDTH</procedure> * in - PPIX * in - SCALEX/Y, SHARPFRAC - {{flaot}}. * in - SHARPWIDTH - {{int}}, 1 or 2. * returns: modified ppix. ** ''(When max scalex/y is < 0.2, no sharpening applied. ** Between .2 and 1.4, sharpen according to input values. ** With scalex/y > 1.4, no sharpening is applied. ** For precise control, call {{pix-scale-general}} with sharpfrac 0.0 followed by call to {{pix-unsharp-mask}}.)'' (define-external ppix0 ppix (pix-read "img0.webp")) (define scaledpix (pix-scale-general ppix0 1.2 1.2 0.25 1)) ... (define res (pix-write scaledpix "img0-1.2x.webp" scaledpix 15)) ;; res -> 0 <procedure>pix-scale-smooth PPIX SCALEX SCALEY</procedure> * in - PPIX * in - SCALEX/Y - {{float}}. ** ''(Scale factors MUST BE <0.7.)'' * returns: modified ppix, or #f on error. <procedure>pix-scale-to-size PPIX WIDTH HEIGHT</procedure> * in - PPIX * in - WIDTH/HEIGHT - {{int32}} - pixels. ** ''(To preserve aspect ratio, set width 0, use height as target. Or set height to 0 to use width as target.)'' * returns: modified ppix or #f on error. ==== Unsharp mask <procedure>pix-unsharp-mask PPIX SMOOTHING AMOUNT</procedure> * in - PPIX * in - SMOOTHING - filter is odd {{int}} such as 3, 5, 7. Input is halfwidth = (size - 1)/2, ''i.e.'', 1, 2, 3. * in - AMOUNT is {{float}}, typically in range 0.2 to 0.7. * returns: modified ppix. <procedure>pix-unsharp-mask-fast PPIX HALFWIDTH AMOUNT DIRECTION</procedure> * in - PPIX * in - HALFWIDTH - {{int}}, 1 or 2 * in - AMOUNT = {{float}}, 0.2 to 0.7 * in - DIRECTION - {{int}}, horz: 1, vert: 2, both: 3 * returns: modified ppix. ==== Pixel data input/output <procedure>pix-create WIDTH HEIGHT DEPTH</procedure> * in - WIDTH/HEIGHT - {{int32}}, in pixels. * in - DEPTH - must be 1, 2, 4, 8, or 32 ** ''(Pix->data is {{ptr to unsigned-int32}}, array length = w''h, elements initialized to 0.)* * returns: ppix on success, #f on error. <procedure>pix-get-data PPIX</procedure> * in - PPIX ** ''(Returned data-array remains “owned” by ppix, array modified in place.)'' * returns: {{ptr to unsigned-int32}} if successful, #f on error. <procedure>pix-extract-data PPIX</procedure> * in - PPIX ** ''(Unlike {{pix-get-data}}, returned value is ptr to newly alloc copy of ppix->data. ppix->data is set to NULL if ppix->refcount == 1.)'' * returns: {{ptr to unsigned-int32}} on success, #f on error. <procedure>pix-set-data PPIX DATAPTR</procedure> * in - PPIX * in - DATAPTR - {{ptr to unsigned-int32}} * returns: 0 if successful, 1 on error. ** ''(Use {{pix-free-data}} prior to setting ppix data.)'' <procedure>pix-get-pixel PPIX X Y PTR-PIXVAL</procedure> * in - PPIX * in - X, Y - {{int32}} - raster position * out - PTR-PIXVAL - {{ptr to unsigned-int32}} * returns: 0 on success, 1 on error <procedure>pix-set-pixel PPIX X Y PIXEL-VALUE</procedure> * in - PPIX * in - X, Y - {{int32}} - raster position * in - PIXEL-VALUE - {{unsigned-int32}} * returns: 0 on success, 1 on error <procedure>pix-get-rgb-component PPIX COLOR</procedure> * in - PPIX * in - COLOR - {{int32}}, one of COLOR_RED, COLOR_GREEN, COLOR_BLUE * returns: ppix with data set to COLOR component, #f on error. <procedure>extract-rgb-vals PIXEL PRED PGREEN PBLUE</procedure> * in - a PIXEL - {{unsigned-int32}} * in - PRED, PGREEN, PBLUE - optional, {{ptr to int32}} or #f * returns: no return value. <procedure>pix-get-rgb-line PPIX ROW PR PG PB</procedure> * in - PPIX * in - ROW - {{int32}} * in - PR, PG, PB - {{ptr to unsigned-byte}}, array length = image width * returns: 0 if success, 1 on error. (import chicken.number-vector leptonic) (define red (make-u8vector img-width)) (define green (make-u8vector img-width)) (define blue (make-u8vector img-width)) (define r (pix-get-rgb-line ppix row (location red) (locaton green) (location blue))) (if (zero? r) ;; use red, green, blue vectors ... ;; handle error) <procedure>pix-get-raster-data PPIX PUBYTE PNBYTES</procedure> * in - PPIX * out - PUBYTE - {{ptr to unsigned-byte}}, array-length = w * h * 3 * out - PNBYTES - {{ptr to size_t}} * returns: 0 on success, 1 if error. ==== Image manipulation <procedure>pix-modify-sat PPIXD PPIX SAT</procedure> * in - PPIXD - destination ppix, may be set to #f * in - PPIX * in - SAT - {{float}} - from -1.0 to 1.0 * returns: modified ppix, or #f on error <procedure>pix-invert PPIXD PPIX</procedure> * in - PPIXD - may be #f * in - PPIX * returns: - inverted ppix or #f on error <procedure>pix-and PPIXD PPIX0 PPIX1</procedure> * in - PPIXD - may be #f * in - PPIX0, PPIX1 - image data to be “anded” * returns: - PPIX0 AND PPIX1, or #f on error <procedure>pix-or PPIXD PPIX0 PPIX1</procedure> * in - PPIXD - #f * in - PPIX0, PPIX1 - image data to be “ored” * returns: - PPIX0 OR PPIX1, or #f on error <procedure>pix-xor PPIXD PPIX0 PPIX1</procedure> * in - PPIXD - #f * in - PPIX0, PPIX1 - image data to be “xored” * returns: - PPIX0 XOR PPIX1, or #f on error <procedure>pix-shiftRGB PPIX RFRAC GFRAC BFRAC</procedure> * in - PPIX * in - RFRAC, GFRAC, BFRAC - {{float}} - fractional amount of change per channel * returns: modified ppix or #f on error. <procedure>pix-contrast PPIXD PPIX FACTOR</procedure> * in- PPIXD - dest - #f or PPIX (use ‘pix-contrast PPIX PPIX …’) * in - PPIX * in - FACTOR - amount, 0.0 to 1.0 * returns: modified ppix or #f if error. <procedure>pix-mod-brightness PPIXD PPIX FACTOR</procedure> * in - PPIXD - #f or PPIX * in - PPIX * in - FACTOR - amount -1.0 to 1.0 * returns: modified ppix or #f if error. <procedure>pix-mod-hue PPIXD PPIX FACTOR</procedure> * in - PPIXD - #f or PPIX * in - PPIX * in - FACTOR - amount -1.0 to 1.0 (1.0/-1.0 == 360 degrees, no hue change) * returns: modified ppix or #f if error. <procedure>pix-equalize PPIXD PPIX FRAC SUBSAMPLE</procedure> * in - PPIXD - #f or PPIX * in - PPIX * in - FRAC - 0.0 to 1.0 “equalization movement of pixels”, 1.0 == complete. * in - SUBSAMPLE - factor > 1 => reduced computation * returns: modified ppix or #f if error. <procedure>pix-gamma PPIXD PPIX GAMMA MIN MAX</procedure> * in - PPIXD - #f or PPIX (in-place modification, ({{pix-gamma}} PPIX PPIX ..) ) * in - PPIX * in - GAMMA - 1.0, no change, <1.0 darker, >1.0 lighter * in - M* in - MIN usually >=0, but may be < 0–black will be gray. * in - MAX - MAX usually <= 255, but may be > 255, then whites are gray… * returns: modified ppix or #f if error. <procedure>pix-remove-alpha PPIX</procedure> * in - PPIX * returns: ppix with alpha removed, or #f on error. <procedure>pix-map-to-color PPIXD PPIX SRCVAL DSTVAL</procedure> * in - PPIXD - #f or same as PPIX * in - PPIX * in - SRCVAL - color specified as 0xrrggbb00 * in - DSTVAL - color specified as 0xrrggbb00 * returns: modified ppix or #f if error. <procedure>pix-colorize-gray PPIX PIXEL CMAP?</procedure> * in - PPIX - 8bit (grayscale) * in - PIXEL - 32bit color spec, e.g., 0xrrggbb00 * in - CMAP? - add colormap, 0 or 1 * returns: modified ppix or #f if error. <procedure>pix-bilateral PPIX SPATIAL RANGE NCOMPS REDUCTION</procedure> * in - PPIX * in - SPATIAL - stddev of gaussian kernel, pixels, >0.5 * in - RANGE - stddev of gaussian range kernel, >5.0, typically 50.0 * in - NCOMPS - intermediate sums, 4..30 * in - REDUCTION - 1, 2, 4 * returns: modified ppix or #f if error. <procedure>pix-warp-stereo PPIX ZBEND ZSHIFTT ZSHIFTB YBENDT YBENDB RLEFT</procedure> * in - PPIX * in - ZBEND - {{int}} - horz sep (in px) red/cyan left/right sides * in - ZSHIFTT - {{int}} ** Push top of image plane away (>0) or towards (<0) viewer * in - ZSHIFTB - {{int}} - push bottom of image away or towards viewer * in - YBENDT - {{int}} - ** Param for displacement right/left edge, y= ybendt*(2x/w-1)^2 * in - RLEFT - {{int}} - 1 to put red filter on left, 0 otherwise * returns: modified ppix or #f on error. <procedure>pix-blend-color PPIXD PPIX1 PPIX2 X Y FRACT TRANSPARENT TRANSPIX</procedure> * in - PPIXD - may be #f or same as PPIX * in - PPIX1 - “blendee” * in - PPIX2 - “blender”, usually smaller area than PPIX1 * in - X, Y - origin of PPIX2 relative to origin of PPIX1 (pixels) * in - FRACT - blending fraction * in - TRANSPARENT - 1: use transparency, 0: don’t use transparency. * in - TRANSPIX - color in PPIX2 to be made transparent, typically 0 or 0xffffff00 * returns: blended ppix or #f on error. ==== Image analysis <procedure>pix-sizes-equal PPIX1 PPIX2</procedure> * in - PPIX1 PPIX2 - ppix to compare * returns: 1 if {h,w,d} the same, 0 if not. <procedure>pix-get-pixel-avg PPIX PPIXM X Y FACTOR PVAL</procedure> * in - PPIX * in - PPIXM - (optional) 1bit mask of area to measure, may be #f * in - X Y - UL coords of mask relative to PPIX - ignored if PPIXM is #f * in - FACTOR - subsampling factor 1, 2, 4 * out - PVAL - {{ptr to unsigned-int}} - avg pixel val * returns: 0 if “OK”, 1 on error. <procedure>pix-compare-gray-or-RGB PPIX1 PPIX2 CMPTYPE PLOT PSAME PDIFF PRMSDIFF PPIXDIFF</procedure> * in - PPIX1, PPIX2 - image data to compare * in - CMPTYPE - subtract: 2, abs-diff: 3 * in - PLOT - plot type, use 0 for no plot. * out - PSAME PDIFF PRMSDIFF PPIXPTR - these are optional, use #f to skip. ** PSAME - {{ptr to int32}} - (PSAME = 1 if pixel values identical) ** PDIFF/PRMSDIFF - {{ptr to float}} - (PDIFF: avg diff, PRMS: rms of diff) ** PPIXDIFF - {{ptr to ppix}} - 8bpp (grayscale) - pixel values set to pixel diff * returns: 0 if “OK”, 1 if error. <procedure>pix-color-content PPIX RREF GREF BREF MINGRAY RCONT GCONT BCONT</procedure> * in - PPIX * in - RREF GREF BREF - {{int32}} - reference values for red,green,blue component. ** ''RREF/GREF/BREF must all be 0 or all not 0. When not 0, ref values describe an unbalanced white point, or mean color of background of scanned images. Set to 0 to turn off color transforms.'' * in - MINGRAY - {{int32}} ** ''Pixels less than mingray are set to 0,0,0. set mingray to 0 to turn off filtering dark pixels.'' * out - RCONT GCONT BCONT - {{ptr to ppix}} - (optional, set to #f if unused) ** ''If used, filled with R/G/B 8bpp ppix corresponding to component color content.'' * returns: 0 if “OK”, 1 on error. (import scheme.base leptonic) (include "leptonic-types.scm") (define-external imgpix ppix (pix-read "myimage.jpg")) (define-external rcont ppix) (define-external gcont ppix) (define-external bcont ppix) (define r (pix-color-content imgpix 0 0 0 20 (location rcont) (location gcont) (location bcont))) (if (zero? r) (begin ;; -- use the ppixs: rcont, gcont, bcont -- (pix-destroy (location imgpix)) (pix-destroy (location rcont)) (pix-destroy (location gcont)) (pix-destroy (location bcont))) ;; -- handle error --) <procedure>pix-color-fraction PPIX DARKTHR LIGHTTHR DIFFTHR FACTOR PIXFRAC COLORFRAC</procedure> * in - PPIX - 32bpp * in - DARKTHR - {{int32}} ** ''Threshold near black. Pixels below aren’t included in stats. Typical: 20'' * in - LIGHTTHR - {{int32}} ** ''Threshold near white. Pixels above aren’t included in stats. Typical: 244'' * in - DIFFTHR - {{int32}} ** ''Threshold for max diff between R/G/B values. When diff is less, pixel is considered insufficiently colorful. Typical: 60'' * in - FACTOR - {{int32}} - Subsampling factor, 1, 2, 4. 1 is no subsampling. * out - PIXFRAC - {{ptr to float}} - optional, use #f to skip. ** ''Fraction of pixels considered for color content.'' * out - COLORFRAC - {{ptr to float}} - optional, use #f to skip. ** ''Fraction of pixels meeting criterion for sufficient color. 0.0 on error.'' * returns: 0 if “OK”, 1 on error. <procedure>pix-color-magnitude PPIX RREF GREF BREF TYPE</procedure> * in - PPIX - 32bpp or 8bpp w/cmap * in - RREF GREF BREF - {{int32}} - ''Reference values for red, green, blue components, representing unbalanced white or avg background color of a scanned image. Image colors are adjusted according to the ref values. Set all to 0 to skip this adjustment.'' * in - TYPE - one of intermediate-diff: 1, avg-max-diff: 2, max_diff: 3 * returns: 8bpp ppix (amt of color in each src pixel) or #f on error. ==== Effects <procedure>pix-clean-image PPIX CONTRAST ROTATE SCALE OPEN-SIZE</procedure> * in - PPIX * in - CONTRAST - {{int32}} - 1 (lightest) to 10 (darkest) * in - ROTATE - {{int32}} - 0,1,2,3 (0,90,180,270 degrees cw) * in - SCALE - {{int32}} - 1 or 2 (for 2X upscaling) * in - OPEN-SIZE - {{int32}} - size for noise removal (0/1-none, 2,3 to use) * returns: cleaned ppix or #f if error. <procedure>gen-bin-maze WIDTH HEIGHT X Y SIDEWALL AHEAD</procedure> * in - WIDTH - {{int32}} - image width * in - HEIGHT - {{int32}} - image height * in - X - {{int32}} - x start of maze * in - Y - {{int32}} - y start of maze * in - SIDEWALL - {{float}} - probability of wall to side of direction * in - AHEAD - {{float}} - probability of wall drawn ahead of direction ** ''(Generates binary (monochrome) maze)'' * returns: ppix or #f on error. (import scheme.base chicken.foreign leptonic) (include "leptonic-types.scm") ;; generate maze, 100x75px, starts at x=5,y=70px (define-external maze ppix (gen-bin-maze 100 75 5 70 .52 .48)) (pix-write "maze.jpg" maze 2) (pix-destroy (location maze)) <procedure>pix-sobel-edge-filter PPIX ORIENTATION</procedure> * in - PPIX - 8bpp * in - ORIENTATION - {{int32}} ** edges: horizontal: 0, vertical: 1, all: 2. * returns: 8bpp ppix or #f if error. ==== Dithering <procedure>pix-dither-2bpp PPIX CMAP?</procedure> * in - PPIX - 8bpp/graymap * in - CMAP? - generate colormap? 0=no, 1=yes ** ''Dithers to equally spaced gray values at 0, 85, 170, 255.'' * returns: dithered ppix or #f if error. <procedure>pix-dither-2bpp-spec PPIX LOWCLIP UPCLIP CMAP?</procedure> * in - PPIX - 8bpp/graymap * in - LOWCLIP - lower clipping point, should be 0 or a small number. * in - UPCLIP - upper clipping point, should be 255 or slightly less. * in - CMAP? - generate colormap, 0 or 1. * returns: dithered ppix or #f if error. <procedure>pix-dither-binary PPIX</procedure> * in - PPIX - 8bpp/grayscale image. * returns: dithered ppix or #f if error. <procedure>pix-dither-bin-spec PPIX LOWCLIP UPCLIP</procedure> * in - PPIX - 8bpp * in - LOWCLIP - lower clipping point, should be 0 or a small number. * in - UPCLIP - upper clipping point, should be 255 or slightly less. * returns: dithered ppix or #f if error. ==== Threshold <procedure>pix-threshold-to-binary PPIX THRESH</procedure> * in - PPIX - 4 or 8bpp * in - THRESH - if src pixel is < THRESH, dest is 1, else dest is 0. (Max pixel value for 8bpp == 255, 4bpp == 15.) * returns: dithered 1bpp ppix or #f on error. <procedure>pix-threshold-to-2bpp PPIX NLEVELS CMAP?</procedure> * in - PPIX - 8bpp * in - NLEVELS - 2..4 equally spaced levels in output ppix * in - CMAP? - 0/1 * returns: dithered 2bpp ppix or #f on error. <procedure>pix-threshold-to-4bpp PPIX NLEVELS CMAP?</procedure> * in - PPIX - 8bpp * in - NLEVELS - 2..16 equally spaced levels in output * in - CMAP? - 0/1 * returns: dithered 4bpp ppix or #f on error. <procedure>pix-threshold-on-8bpp PPIX NLEVELS CMAP?</procedure> * in - PPIX - 8bpp * in - NLEVELS - 2..256 equally spaced levels in output * in - CMAP? - 0/1 * returns: dithered 8bpp ppix or #f on error. ==== Conversion <procedure>pix-RGB-to-gray PPIX RWT GWT BWT</procedure> * in - PPIX - 32bpp RGB image * in - RWT GWT BWT - {{float}} values, weights should add up to 1. * returns: 8bpp ppix or #f if error. <procedure>pix-RGB-to-gray-fast PPIX</procedure> * in - PPIX - 32bpp RGB image * returns: 8bpp ppix or #f if error. <procedure>pix->32bit PPIX </procedure> * in - PPIX - 1, 2, 4, 8, 16, 24 or 32 bpp * returns: ppix or #f on error. <procedure>pix->16bit PPIX</procedure> * in - PPIX - 1, 8 bpp * returns: ppix or #f on error. <procedure>pix->8bit PPIX</procedure> * in - PPIX - 1, 2, 4, 8, 16, 24 or 32 bpp * returns: ppix or #f on error. <procedure>pix->4bit PPIX</procedure> * in - PPIX - 1, 2, 4, 8, 24 or 32 bpp * returns: ppix or #f on error. <procedure>pix->2bit PPIX</procedure> * in - PPIX - 1, 2, 4, 8, 24 or 32 bpp * returns: ppix or #f on error. <procedure>pix->1bit PPIX</procedure> * in - PPIX - 1, 2, 4, 8, 16, 24 or 32 bpp * returns: ppix or #f on error. <procedure>pix-RGB->HSV PPIXD PPIX</procedure> * in - PPIXD - #f * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-HSV->RGB PPIXD PPIX</procedure> * in - PPIXD - #f * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-RGB->XYZ PPIX</procedure> * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-RGB->YUV PPIXD PPIX</procedure> * in - PPIXD - #f * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-YUV->RGB PPIXD PPIX</procedure> * in - PPIXD - #f * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-RGB->hue PPIX</procedure> * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-RGB->sat PPIX</procedure> * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-RGB->value PPIX</procedure> * in - PPIX * returns: converted ppix or #f on error. <procedure>pix-RGB->Lab PPIX</procedure> * in - ppix * returns: converted PFPIXA or #f on error. <procedure>fpixa-Lab->RGB PFPIXA</procedure> * in - PFPIXA (Lab) * returns: converted PPIX or #f on error. <procedure>fpixa-Lab->XYZ PFPIXA</procedure> * in - PFPIXA (Lab) * returns: converted PFPIXA or #f on error. <procedure>fpixa-XYZ->Lab PFPIXA</procedure> * in - PFPIXA (XYZ) * returns: converted PFPIXA or #f on error. <procedure>fpixa-XYZ->RGB PFPIXA</procedure> * in - PFPIXA (XYZ) * returns: converted PPIX or #f on error. ==== Error messages <procedure>set-msg-level LEVEL</procedure> * in - LEVEL {{int32}} - 1:all 2:debug+ 3:info+ 4:warn+ 5:error+ 6:none * returns: - old level {{int32}} ==== Serializing data 32bit to 8bit, 8bit to 32bit These routines are not from leptonica, but provided to facilitate conversion of 32 bpp data to 8 bpp arrays (in RGB order) and vice versa. <procedure>u32->u8''3 PTR32 LEN PTR8*</procedure> * in - PTR32 - {{ptr to unsigned-int32}} * in - LEN - {{int}} - length of data - (image width * height) * out - PTR8 - {{ptr to unsigned-byte}} * returns: number of 32bit pixels (should be equal to LEN) <procedure>u8''3->u32 PTR8 LEN PTR32*</procedure> * in - PTR8 - {{ptr to unsigned-byte}} * in - LEN - {{int}} - length of data (image width * height) * out - PTR32 - {{ptr to unsigned-int32}} * returns: number of 32bit pixels (should be equal to LEN) (import scheme.base chicken.foreign chicken.number-vector leptonic) (include "leptonic-types.scm") (define-external ppx0 ppix (pix-read "input.png")) (define data0 (pix-get-data ppx0)) (define w (pix-get-width ppx0)) (define h (pix-get-height ppx0)) (define len (* w h)) (define v8 (make-u8vector (* len 3) 0)) (u32->u8*3 data0 len (location v8)) ;; ... modify v8 ... (define-external ppx1 ppix (pix-create w h 32)) (define data1 (pix-get-data ppx1)) (u8*3->u32 (location v8) len data1) (define fmt (get-implied-fmt "output.png")) (pix-write "output.png" ppx1 fmt) (pix-destroy (location ppx0)) (pix-destroy (location ppx1)) Note: if u8vector ‘v8’ is ''not'' modified, then output to data1 (in u8*3->u32), will be identical to the input data in data0. IOW “output.png” will be a copy of “input.png”. Comparing the two image files serves as a test of the procedures: if everything is working properly, the image files should be completely indistinguishable. === Versions * 0.1.0 (initial release) Description of your changes:

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