[Gimp-developer] Porting GIMP plugins to GEGL operations - GSOC 2011
Hello sir, I am Shivani 2nd year student at IIIT-Allahabad( Indian Institute Of Information Technology, Allahabad ). I have a programming experience with C, C++,QT and Java. Besides this I have also worked with OpenGl(glut/glu). I have Graphics Visualization and Computing as one of the core subject of this semester. Studying the plugins I find it very similar to using a combination of QT and opengl. I am very eagerly interested in Image Manipulations and designing and I would like to contribute to porting the plugins to GEGL operations.Currently I am working on designing an UCI chess engine ( coding in C++ ) and making a virtual tour of my college campus by opengl.Both of the projects will be complete by the end of April. Here is the code review and algorithm for the major files specified as a test ( please correct me if I am wrong ) - *Cubism *- header file - libgimp/gimp.h makes all basic plugin elements available to us. Structures defined- 1. Polygon - containing detail for polygon construction 2. CubismVals - holds details for generation of tiles such as -tile saturation , tile size, background color and bool preview. background color - if no bg color specified then black is used while applying the filter. tile size - determines size( in pixels ) of the square to be used. tile saturation- determines the intensity of the color of the squares thereby defining the opacity of square. Local Variables - 1. cvals - storing default values for the parameters of the structure CubismVals. 2. GimpPlugInInfo PLUG_IN_INFO - Contains four pointers to different functions which are called during plugin execution. a)init - optional(can have null value) and is called as GIMP starts up. It can be called if we want to register some procedure conditionally on some files prescence. b)quit - also optional( can have null value ) and is called when GIMP is going to close. c)query - called when the plugin comes into existence or every time when it is modified. d)run - it is the plugin processing function which receives the plugin name, input parameters, number of return values, pointer to output parameters. MAIN() - it is a macro defined for calling the initialisation and calling appropriate functions that our plugin needs during its life time. Functions - 1. query() - defines the input arguments Structure GimpParamDef contains - type, name and description. It registers the function in the path specified as here under Image/Filters/Artistic 2. cubism_dialog (GimpDrawable *drawable) - opens a dialog box for the user for specifying the basic input parameters. This also function holds the basic layout informaion for the dialog box. It clearly mentions the existence of two scale bars ( tile saturation,tile size ), preview window, toggle button( use background color ) and ok button. User can change the value of parameters and have a preview for every changed argument.The widget does not gets destroyed until the ok button( signal - GTK_RESPONSE_OK ) or cancel button is pressed and the final parameters are then saved. 3. cubism (GimpDrawable *drawable,GimpPreview *preview) - Every variable of the GimpDrawable struct has a drawable id, width, height,bytes per pixel,number of tile rows, number of tile columns, normal tiles and shadow tiles. Here we check if the drawable has an alpha channel associated with it. Alpha channel can be there with the layer types such as RGB, GRAYSCALE and it defines the amount of opacity of the layer. Here in this function it checks whether cubism effect has to be applied in the preview window or on the main image and accordingly performs the task. For preview window - It gets the preview window position and the preview area width, preview area height sets the bound and allocates 'sel_height * sel_width * bytes' memory locations of type guchar all initialised to 0 and pointed by dest. If not preview - then directly set bounds based on drawable-id Now we determine the background color. If it is set as default 'Black' then we initialise the bg_col array with 0, otherwise we get the background color and set the bg_col array with it. Then we calculate the number of rows and columns based on tile_size. It fills the image based on the background color. If it is for preview then it directly assigns each destination byte with the color in bg_color. Otherwise - While creating the cubistic transformation it displays the progress bar having a label - 'Cubistic Transformation' . It now loops through every pixel and initialises the background color to the colour of the original image.Now based on the number of rows and columns it calculates the number of tiles. Initialise a pixel region pointed by src_rgn ,new region being attached to drawable region, (x1,y1) as initial coordinates, width as (x2-x1)and height as (y2-y1).Based on tile size and random indices it calculates the random starting points( x, y ), then random width and height and random angle( theta ). It initialises a
[Gimp-developer] Porting GIMP plugins to GEGL operations - GSOC 2011
Here are the other 3 files . I had to post in two different mails on account of size exceeding the limit of mail *Gaussian blur-* * * Functions - 1.iir_young_find_constants (gfloat sigma, gdouble *B, gdouble *b) - Based on sigma( standard deviation of Gaussian distribution ) we calculate the constants. If sigma == 0 then to prevent ringing at the tile boundaries we define *B = 1 and b[0]=1,b[1]=b[2]=b[3]=0 else the value of the constants depend upon the parameter 'q'. 2. iir_young_blur_1D (gfloat * buf,gint offset, gint delta_offset, gdouble B, gdouble * b, gfloat *w, gint w_len)- in the forward filter we increase the offset every time we iterate by an amount = delta_offset till we reach the end. In backward filter we begin from the other extreme and every time we iterate to the left we decrease the offset by an amount = delta_offset 3. iir_young_hor_blur (GeglBuffer *src, const GeglRectangle *src_rect,GeglBuffer *dst,const GeglRectangle *dst_rect, gdouble B, gdouble *b) - This is for INFINITE IMPULSE RESPONSE.Produces the horizontal blurring in the image.It expects the source and destination to be of same height and 0 y offset. 4. iir_young_ver_blur (GeglBuffer *src, const GeglRectangle *src_rect,GeglBuffer *dst,const GeglRectangle *dst_rect, gdouble B, gdouble *b) - This is for INFINITE IMPULSE RESPONSE.Produces the vertical blurring in the image.It expects the source and destination to be of same width and 0 x offset. 5. fir_calc_convolve_matrix_length (gdouble sigma) - calculates the length of convolution matrix depending upon the standard deviation. 6. fir_gen_convolve_matrix (gdouble sigma, gdouble **cmatrix_p) - produces the convolution matrix cmatrix_p which is applied to the original image to produce gaussian blur.Each pixel's new value is set to a weighted average of that pixel's neighborhood. The original pixel's value receives the heaviest weight (having the highest Gaussian value) and neighboring pixels receive smaller weights as their distance to the original pixel increases. 7. fir_young_hor_blur (GeglBuffer *src, const GeglRectangle *src_rect,GeglBuffer *dst,const GeglRectangle *dst_rect, gdouble B, gdouble *b) - Calculates horizontal blur for FINITE IMPULSE RESPONSE.It expects the source and destination to be of same height and 0 y offset. 8. fir_young_ver_blur (GeglBuffer *src, const GeglRectangle *src_rect,GeglBuffer *dst,const GeglRectangle *dst_rect, gdouble B, gdouble *b) - Calculates vertical blur for FINITE IMPULSE RESPONSE.It expects the source and destination to be of same width and 0 x offset. 9.process (GeglOperation *operation, GeglBuffer *input,GeglBuffer *output, const GeglRectangle *result)- GeglOperationAreaFilter base class allows defining operations where output data depends upon a neighbourhood with an input window that extends beyond the output window, the information about needed extra pixels in different directions should be set up in the prepare callback for the operation.Based on 'iir' or 'fir' it blurifies the image first horizontally and then vertically with different sets of functions used for both cases. *Extras -* * * *Cartoon - * * * header file - libgimp/gimp.h makes all basic plugin elements available to us. Structures defined- 1. CartoonVals - holds parameters - mask_radius,threshold,pct_black mask_radius - size of area the filter works upon threshold - relative intensity difference which will result in darkening pct_black - decides the amount of black color added to the image Local Variables - 1. cvals - storing default values for the parameters of the structure CartoonVals. 2. GimpPlugInInfo PLUG_IN_INFO - Contains four pointers to different functions which are called during plugin execution. a)init - optional(can have null value) and is called as GIMP starts up. It can be called if we want to register some procedure conditionally on some files prescence. b)quit - also optional( can have null value ) and is called when GIMP is going to close. c)query - called when the plugin comes into existence or every time when it is modified. d)run - it is the plugin processing function which receives the plugin name, input parameters, number of return values, pointer to output parameters. MAIN() - it is a macro defined for calling the initialisation and calling appropriate functions that our plugin needs during its life time. Functions - 1. query() - defines the input arguments Structure GimpParamDef contains - type, name and description. It registers the function in the path specified as here under Image/Filters/Artistic 2. cartoon_dialog (GimpDrawable *drawable) - opens a dialog box for the user for specifying the basic input parameters. This also function holds the basic layout informaion for the dialog box. It clearly mentions the existence of two scale bars ( mask radius, percent black ), preview window and ok button. User can change the value of parameters and have a preview for every changed argument.The widget does
