This sketch / library is built upon experimentation, so trying things out and figuring out what you like is really where the fun begins. Making your own functions out of nested functions is extremely easy, since everything returns an image (as a PImage object).

 IMAGE FUNCTIONS

 new_blank(image) -- returns PImage, creates a new image in the processing window size

rebuffer() -- returns nothing, clears the canvas

 rasterize_buffer(image) -- returns PImage, rasterizes whatever you're working on

 display(image) -- returns nothing, displays the current image

flipHorizontal(PImage img) -- returns PImage

flipVertical(PImage img) -- returns PImage

 save_rando() -- returns nothing, and saves the current image as "(random number).jpg"

 IMAGE COPY FUNCTIONS

 new_copy(image) -- returns PImage

 dark_copy(image, threshold) -- returns PImage

 light_copy(image, threshold) -- returns PImage

 red_copy(image, threshold) -- returns PImage

 green_copy(image, threshold) -- returns PImage

 blue_copy(image, threshold) -- returns PImage

 yellow_copy(image, threshold) -- returns PImage

 pink_copy(image, threshold) -- returns PImage

 aqua_copy(image, threshold) -- returns PImage

 COLOR INVERSION FUNCTIONS

 invert_red(image) -- returns PImage

 invert_green(image) -- returns PImage

 invert_blue(image) -- returns PImage

 invert_yellow(image) -- returns PImage

 invert_pink(image) -- returns PImage

 invert_aqua(image) -- returns PImage

 invert_all(image) -- returns PImage

 EXTRACTION // ASSEMBLY FUNCTIONS

 extract_red(PImage image) -- returns PImage

 extract_green(PImage image) -- returns PImage

 extract_blue(PImage image) -- returns PImage

 extract_hue(PImage image) -- returns PImage

 extract_saturation(PImage image) -- returns PImage

 extract_brightness(PImage image) -- returns PImage

 assemble_RGB(PImage red_img, PImage green_img, PImage blue_img) -- returns PImage

 assemble_HSB(PImage red_img, PImage green_img, PImage blue_img) -- returns PImage

 ALPHA MASKS

 remove_black_pixels(PImage image, float threshold) -- returns PImage

 remove_white_pixels(PImage image, float threshold) -- returns PImage

 remove_red_pixels(PImage image, float threshold) -- returns PImage

 remove_green_pixels(PImage image, float threshold) -- returns PImage

 remove_blue_pixels(PImage image, float threshold) -- returns PImage

FILTERS AND BLENDS  

 thresh_filer(image, threshold) -- returns PImage
 posterize_filter(PImage image, float threshold) -- returns PImage

 gray_filter(PImage image) -- returns PImage

 erode_filter(PImage image) -- returns PImage

 blur_filter(PImage image, float threshold) -- returns PImage

 filterer(PImage image, int mode) -- returns PImage

 filter_thresh(PImage image, int mode, float thresh) -- returns PImage

 DEPENDENCIES

 detectEdges(PImage img, float scale) -- returns PImage

 applyGaussianBlur(PImage img, int radius) -- returns PImage

 createGaussianKernel(int radius) -- returns PImage

 applySharpen(PImage img) -- returns PImage

 applySepia(PImage img) -- returns PImage

 applyThreshold(PImage img, float threshold) -- returns PImage

 applyInversion(PImage img) -- returns PImage

 detectEdgesCanny(PImage img) -- returns PImage

 applyEmboss(PImage img) -- returns PImage

 applyPixelation(PImage img, int pixelSize) -- returns PImage

 applyVignette(PImage img, float intensity) -- returns PImage

 applyColorize(PImage img, color tintColor) -- returns PImage

SORTING ALGORITHMS 

 sorter(PImage img)

 dark_sort(PImage img, float threshold)

 bright_sort(PImage img, float threshold)

 red_sort(PImage img, float threshold)

 green_sort(PImage img, float threshold)

 blue_sort(PImage img, float threshold)

 edge_sort_dark(PImage img, float tolerance, float threshold)

 edge_sort_bright(PImage img, float tolerance, float threshold)

 insertionSortImage(PImage img)

 heapSortImage(PImage img)

 selectionSortImage(PImage img)

 countingSortImage(PImage img)

 shellSortImage(PImage img)

 radixSortImage(PImage img)

 bucketSortImage(PImage img)

 optimizedCountingSortImage(PImage img)

 combSortImage(PImage img)

 gnomeSortImage(PImage img)

 pigeonholeSortImage(PImage img)

 sleepSortImage(PImage img)

 strandSortImage(PImage img)

 oddEvenSortImage(PImage img)

 bogoSortImage(PImage img)

 brickSortImage(PImage img)

 lineSortImage(PImage img)

 enhancedLineSortImage(PImage img)

 horizontalLineSortImage(PImage img)

 verticalLineSortImage(PImage img)

 verticalStripSortImage(PImage img)

 dynamicLineSortImage(PImage img)

 timSortImage(PImage img)

 horizontalStripSortImage(PImage img)

 combinedStripSortImage(PImage img)

 edgeAwareLineSortImage(PImage img)

 createEdgeImage(PImage img)

 refinedDynamicLineSortImage(PImage img)

 applyDynamicLineSorting(PImage img)

 applySporadicPixelDistortion(PImage img)

 applyGradientSortEffect(PImage img)

 createArtisticPixelSort(PImage img)

 artisticPixelSortWithShapePreservation(PImage img)

 artisticPixelTransform(PImage img)

 surrealPixelRearrange(PImage img)

 artisticPixelFlow(PImage img)

 creativePixelSort(PImage img)

 surrealPixelTwist(PImage img)

 pixelDripEffect(PImage img)

COMPOUND FUNCTIONS

 candleWaxBrightEdge(PImage img, float threshold)

 candleWaxDarkEdge(PImage img, float threshold)

 lineSortDarkEdge(PImage img, float threshold)

 lineSortBrightEdge(PImage img, float threshold)

flipFlopSnowballEffect(int amt)

darkSnowballEffect(int amt)

lightSnowballEffect(int amt)

 More to come!