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Text File | 1993-06-22 | 28.3 KB | 803 lines

>Guide ----------------------------------------------------------------------------- This program is SHAREWARE. It is *not* free software. You may evaluate it for a two-week trial period. After this, you are required to register for further usage, or else destroy your copy. Refer to the end of this guide for details. ----------------------------------------------------------------------------- _______________________________________________________________________________ GreyEdit 1.35 --------------------------- This program is SHAREWARE Version date : 22 Jun 1993 --------------------------- ---------------- - Introduction - ---------------- GreyEdit can process and edit 256-level greyscale (digitized) images. In addition it can grab video images from the Zeridajh Video Digitiser podule, when this is present. Several extremely fast filter algorithms, histogram equalization, range expansion and inversion may be applied to whole images. In addition, noise pixels may be edited by hand, and sides of images may be cut off, optionally aided by zoom functions for precision editing. ------------------------- - Using the application - ------------------------- To start up GreyEdit, double-click on the '!GreyEdit' icon. It will install itself on the icon bar, and clicking MENU on GreyEdit's icon pops up the main menu, giving the usual 'Info' and 'Quit' options, and others, which will be discussed further on. The main menu is also popped up when clicking MENU on the image window, once an image is loaded. ----------------- - The main menu - ----------------- This menu, popped up by clicking MENU on GreyEdit's iconbar icon, or clicking MENU on an image window, contains a number of icons (some of which lead to submenu's/windows). The functions of the icons will be discussed below. The main purpose of the main menu is to provide access to GreyEdit's control window (via the 'Control' icon), which contains (in groups) most of the available options and controls. -------------- | Image info | -------------- This icon gives access to an information window, in which the resolution, filename, etc. of the current image is displayed. Clicking on this icon will make this window permanent (but it can be closed again by clicking on its close icon). ----------- | Control | ----------- Gives access to GreyEdit's control window, which contains most of GreyEdit's options and controls, divided into groups. Clicking on this icon will make this window permanent (but it can be closed again by clicking on its close icon). Clicking MENU on the control window pops up a menu with short-hands for all the groups. Clicking on one 'pan's to the appropiate group. Several types of icons appear in the control window : - Toggle icons. These are square, and clicking on them switches the corresponding option on (red square in its middle) or off ('closed' box). - Radio icon sets. Icons in these sets are diamond shaped, and act like the toggle icons, but only one of them may be on. Switching any one on will switch off all the others in the same set (hence the name 'radio' icons). - Writable icons. These are square icons with a border and a white background, in which you may click an subsequently enter a value or text. - Button icons. These are round, and clicking on them executes some function. They do not change their appearance when clicked on. - 'Up/down' button icons. These are triangular, and increase or decrease some value in the writable icon in between them. When clicking ADJUST instead of SELECT or MENU, 'up' decreases and 'down' increases (i.e. reverse). These icons are mainly used in the scaling and zoom groups. The functions of the icons in the control window are discussed below. Icons are identified by giving their 'path', i.e. group name (name on the border surrounding the group), if appropiate followed by sub-category (medium grey heading), followed by the icon's own name, seperated by '|'s. \\\\\\\\\ Process ///////// Functions to do with image processing. There are several fast image filters and an option to switch on pixel-editing and cutting, among others. For more technical details on the image processing algorithms, refer to 'Technical details'. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Process | Expand range ////////////////////////////////// Clicking on this button will expand the greyvalue range of the image. This algorithm determines the lowest and highest used greyvalues in the image, and expands the range between these values to the full 0-255 range. This increases the visual contrast of images that do not use the full available greyscale range. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Process | Equalize ////////////////////////////// Clicking on this button will perform 'histogram equalization' on the image. This algorithm effectively measures the greyvalue contents of the image and attempts to balance greyvalue use. It can have a dramatic enhancing effect on some images. However, on low-contrast images it can have an equally dramatic degrading effect (they become much lighter and more 'harsh'). \\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Process | Invert //////////////////////////// Clicking on this button will 'invert' the image. This means that the entire greyvalue scale from black to white is reversed, thus producing a 'negative' image. Its effect may be reversed by using it a second time. \\\\\\\\\\\\\\\\\\ Process | Filter ////////////////// Clicking on these buttons applies a particular filter algorithm on the image. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Noise (soft) ///////////////////////////////// This filter will remove noise from the image. This is the 'soft' version of the noise removal filters, which generally does not affect many pixels which are not 'noise pixels', but has the disadvantage that it will usually not succeed in removing all the noise from an image either. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Noise (strong) /////////////////////////////////// This filter, like the soft noise filter, will remove noise from the image. This 'strong' version will (as its name suggests) remove more noise, but has the disadvantage of possibly affecting much more pixels which aren't noise. \\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Gauss ////////////////////////// This 'lowpass' filter has the effect of 'smoothing' the image. The smoothing effect is somewhat weaker than that of the Average filter. As a 'smoother', it also effectively removes noise from the image, but the noise filters should be used by preference to do this, as a lot of image detail is lost using smoothing filters. \\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Average //////////////////////////// This 'lowpass' filter is similar to the Gauss filter, but has a stronger 'smoothing' effect. \\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Laplace //////////////////////////// This 'highpass' filter will, in contrast to the Gauss and Average filters, enhance detail in the image. It has the effect of amplifying local image details, but frequently has the side-effect of making the image look rather 'harsh'. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | X-gradient Sobel ///////////////////////////////////// This filter effectively has a kind of '3-D' effect on the image. It reacts on horizontal 'gradients' in the image. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Y-gradient Sobel ///////////////////////////////////// This filter is similar to the X-gradient Sobel filter, but reacts on vertical 'gradients' in the image. \\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Maximum //////////////////////////// This filter amplifies the presence of the peak greyvalues in the image. \\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Minimum //////////////////////////// This filter amplifies the presence of the lowest greyvalues in the image. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Sharpen (soft) /////////////////////////////////// This filter sharpens the image in a quite subtle way. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Sharpen (strong) ///////////////////////////////////// This filter sharpens the image more harshly than the soft version. \\\\\\\\\\\\\\\\\\\\\\\\ Process | Filter | Lee //////////////////////// This filter 'crispens' the image. \\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Options | Edit ////////////////////////// Toggles the 'edit' flag. When ON, the image may be edited using the mouse pointer. While the mouse pointer is in the image window, its center will change to the greyvalue of the pixel underneath it, so it is easier to identify a particular pixel among others. Pixel editing ------------- Pressing SELECT or ADJUST on a particular pixel enables you to remove noise pixels by hand : - SELECT will change the greyvalue of the pixel to the average greyvalue of its surrounding neighbors, i.e. it adds all eight surrounding pixels' greyvalues and assigns this value DIV 8 to the target pixel. This 'smooths out' noisy pixels which can thus be removed with accuracy by hand, in preference to using the noise or smoothing filters. - ADJUST has a similar effect, except the target pixel's greyvalue itself is considered in the averaging, i.e. the eight surrounding pixels' greyvalues and the target pixel's greyvalue are added, and the resulting value DIV 9 is assigned to the target pixel. This is equivalent to what the 'Average' filter does. Cutting ------- Pressing SELECT or ADJUST while holding down the SHIFT key enables you to cut off the top/left or bottom/right parts of the image : - SELECT will cut off the top/left part of the image : the pixel clicked on will become the new top left pixel - ADJUST will cut off the bottom/right part of the image : the pixel clicked on will become the new bottom right pixel NOTE : The zoom options may be used while editing, so it is very easy to locate and 'kill' individual pixels, and perform precision cutting. The pixel info window (see below) is useful as a further aid in precision cutting and editing. \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Process | Options | Pixel info //////////////////////////////// Clicking on this button will pop up the pixel info window. When editing is enabled, this shows the coordinates and greyvalue of the pixel at the mouse pointer. The top coordinates shown in the window are pixel offsets from the top left of the image, while the bottom pair represents the offsets from the bottom right of the image. This information may help when, for example, cutting has to be very precise (i.e. you know the number of pixels you want to cut off from the sides). \\\\\\\\\\\ Digitiser /////////// This groups the digitiser controls. It is only accessible when the Zeridajh Video Digitiser podule is present. When the podule is not present, the icons will have no effect. They enable you to control the digitiser and grab images. \\\\\\\\\\\\\\\\\\\\\\\\\ Digitiser | Sensitivity *** ///////////////////////// This slider bar may be used to control the sensitivity of the podule to the video signal. The sensitivity may be changed from 0 (least sensitive) to 100% (most sensitive) by either dragging the slider, or clicking on the 'up'/'down' buttons to increase/decrease the sensitivity. The slider bar may only be used when the software-controlled sensitivity extension (a special chip and some rewiring) is present on the podule. Otherwise, attempts at manipulation of the slider will have no effect, and the sensitivity must be controlled by using the potmeter at the back of the podule. \\\\\\\\\\\\\\\\\\\\\\\ Digitiser | Line skip *** /////////////////////// In this writable icon you may enter the 'line skip' factor. The line skip factor is the number of scanlines that will be skipped at the top of the video image that is being digitised. A value of zero selects the default line skip (an equal number of scanlines above and below the picture is skipped). Any positive number may be entered, but, as a video image has a limited number of scanlines, values that are too large may cause the resulting image to be distorted. \\\\\\\\\\\\\\\\\\ Digitiser | Size *** ////////////////// These two radio icon sets enable you to set the X and Y size of the image to be grabbed. Three resolutions are available for both X (640,320,160) and Y (512,256,128). \\\\\\\\\\\\\\\\\\\\\\\\\\ Digitiser | Input switch ////////////////////////// This radio icon set lets you select one of four available video inputs. This option is only available when the colour extension (a special chip and extra circuitry) is present on the podule. Otherwise, you cannot select any other input than the black & white input (which is the only input when the colour extension is not present). \\\\\\\\\\\\\\\\\\\\\\\\ Digitiser | Grab image //////////////////////// Clicking on this button will grab a new (black & white) image. \\\\\\\\\\\\\\\\\\\\\\\\\ Digitiser | Grab colour ///////////////////////// Clicking on this button will grab, in sequence, an image from the red, green and blue inputs. Grabbing starts after dragging the directory icon in the save window that has popped up to a directory viewer. The images will be saved as Clear files 'R', 'G' and 'B' in this directory. The 'R','G' and 'B' greyscale Clear files may subsequently be edited (by reloading them into GreyEdit), and may be mixed to a full 24-bit RGB colour Clear file (see 'Mixing colour'). This option is only available when the colour extension is present on the podule (see 'Input switch'). \\\\\\\\\\\\\\\\\\\\\\\\\\ Digitiser | Video signal ////////////////////////// Clicking on this button temporarily pops up a video signal window. This window will graphically display the synchronisation signals present in the video signal and enables strange or non-standard video signals to be identified. A rough classification of the present video signal is given at the bottom of the window (usually 'No video signal' or 'Normal video signal'). The signal plotted represents the exclusive or of the vsync and hsync signals. Clicking any mouse button will abort the plotting (when not finished) and close the window. \\\\\\ Misc ////// This groups miscellaneous options. \\\\\\\\\\\\\\\\\\\\\\\ Misc | Auto | Palette *** /////////////////////// Toggles the 'auto palette' flag. When ON, a greyscale palette is automatically selected when the image is first popped up, or after changing mode. In fact, the effect is exactly the same as clicking on the 'Grey palette' icon, refer to its discussion for more details. \\\\\\\\\\\\\\\\\\\\ Misc | Auto | Zoom *** //////////////////// Toggles the 'auto zoom' flag. When ON, then when the image is first popped up, or after changing mode, the image is automatically zoomed in or out (see the discussion of the zoom options elsewhere) so that it fits exactly on the screen. \\\\\\\\\\\\\\\\\\\\\ Misc | Grey palette ///////////////////// Clicking on this button will select a greyscale palette from black to white. NOTE : In 256-colour modes, the palette remains unchanged, as it is not possible to get more than 16 shades of grey by changing it. Refer to 'Displaying greyvalues' for more details. \\\\\\\\\\\\\\\ Misc | Create /////////////// Clicking on this button will create a blank image. The size of the image may be entered in the writable icons behind this button. \\\\\\\\\\\\\\\\\ Misc | Patterns ///////////////// These buttons allow the current image to be filled with a computed pattern. This may be useful in experimentation or, for example, creation of 'special effects' images (e.g. for desktop icons). Clicking on one of the 'pattern' icons will create the pattern shown. Most patterns apply the entire greyscale from black to white, e.g. the 'blinds' pattern consists of lines from greyvalue 0 (top) to 255 (bottom), and as much greyvalues in between as the resolution allows. \\\\\\ Zoom ////// This group contains controls with which the image may be zoomed in or out. The X and Y zoom ratios may be entered seperately, and the up/down buttons increment/decrement the multiplier/divisor. In addition, clicking MENU over either the 'X' or 'Y' icon pops up a menu with preset zoom factors for X and Y respectively, which enables quick common selections. To let manually entered zoom factors take effect, click on the button at the far left of the window. The image window's title will indicate how much the original image is enlarged or reduced, by showing a percentage. \\\\\\ Save ////// This icon leads to a save file window, in which the current image may be saved either as a Clear file, or as a (tweaked) sprite file by entering a (leaf) filename and dragging the filetype icon to a directory viewer. \\\\\\\\\\\\\ Save | Save *** ///////////// These radio icons enable selection of a Clear or a sprite file. - Clear The Clear file saved will be 8-bit grey-scale. Further processing (scale, rotate, mirror, Floyd-Steinberg dithering, etc.) or conversion to other graphics formats may be performed by using my other image processing applications Translator and Creator respectively. Refer to the end of this guide for more details. - Sprite The Sprite file saved will be 8-bit, with no palette (i.e. standard palette actually). The greyvalues of the image are mapped (1-1) to the closest colours in the standard 256-colour palette that represent them when the sprite is displayed on a monochrome monitor. \\\\\\\\\\\\\\\\\\ Save | Auto name *** ////////////////// Toggles the 'auto name' flag. When ON, the leafnames for files to be saved are generated automatically from a list that may be entered in the writable icon below the toggle icon. The list consists of leafnames, seperated by comma's. The leafnames are taken cyclically from this list, so 'R,G,B' generates 'R', then 'G', then 'B', then 'R', then 'G', etc.. The current leafname is reset to the first in the list by switching 'Auto name' to ON. So, if, for any reason, you want to reset the current leafname to the first one in the list, simply switch the 'auto name' flag off, then on again. ---------- | Status | ---------- This icon gives access to a submenu of status handling functions. GreyEdit's status consists of all the items marked ***. - Save Clicking on this icon will save the current status in GreyEdit's status file. This file (when present) is always loaded on startup, or may be explicitly loaded by using the 'Load' option (to override the current status). - Load Clicking on this icon explicitly (re-)loads the status file, overriding the current status. - Default Clicking on this icon selects the default status settings. - Kill Clicking on this icon will remove the status file. 'Standard' defaults will be used when GreyEdit is next started up. ----------------- - Mixing colour - ----------------- A triple of 'red','green' and 'blue' Clear files may be mixed to a full 24-bit RGB colour Clear file by GreyEdit. To do this, the following must apply : - The three component files must be of the same resolution - The red, green and blue component files must be saved inside a directory as 'R','G' and 'B' respectively. Dragging the directory's icon to GreyEdit's iconbar icon or one of its windows will pop up a save window, in which the leafname of the resulting 24-bit RGB Clear file may be entered (it will default to the directory name). Dragging the Clear icon to a directory viewer will then mix the three component files. The 24-bit RGB Clear file may be viewed using Translator (see end of this guide for more details on Translator). ------------------------- - Displaying greyvalues - ------------------------- As the Archimedes can display only 16 shades of grey, it is not possible to give a correct representation of the full 0-255 greyscale range of the image, even in 256 colour modes. In 16, 4 and 2 colour modes, a selection of the 16 available greys is made to create a scale from black to white, and the full greyscale is simply mapped to the closest of these greys. In 256-colour modes (and when saving an image as a sprite), the full greyscale of the image is mapped (1-1) to the colours of the standard 256-colour palette which closely represent them when the sprite is being displayed on a monochrome monitor (for example, using the mono video output on the back of the Archimedes). This is the only way to get more shades of grey on-screen. To get the best possible result on colour monitors (i.e. using a maximum of 16 shades of grey), save the image as a Clear file and use Translator's Floyd-Steinberg dithering option (and the 'Current mode' and 'Greyscale' palette settings when dithering to non-256 colour modes). --------------------- - Technical details - --------------------- - The GreyEdit module The SWI's contained in the GreyEdit module may be useful to users that wish to build their own image processing or digitizing applications. Refer to the file Docs.SWIs for detailed descriptions. - Image filters The filters apply a 'local' filtering algorithm to the image. Most filters are '3x3 local neighborhood' filters, which means that for every pixel in the image, the surrounding eight pixels are considered, together with the current value of the pixel, to compute a new pixel value according to the algorithm used. Most algorithms attach 'weights' to these 9 pixels and calculate the new greyvalue by adding all (or some of) the pixel values, multiplied with these weights, and then divide the result by the total weight to average it. All these filters map any pixels lying 'outside' the image to the nearest image pixel (i.e. this occurs for all target pixels at the 4 borders). The individual filters are discussed below. The 'target' pixel is always the 'middle' pixel, and these terms are used interchangably. The number of pixels in the neighborhood of this 'middle' pixel that are considered depends on the filter. Noise (soft) ------------ If the pixel left to the target pixel is equal (in greyvalue) to the right pixel, the middle pixel is replaced with the left (=right) pixel value. Noise (strong) -------------- If the target pixel is either the maximum or the minimum among the north, south, east and west pixels, it is replaced with the average value of the north, south, east and west pixels (this is usually called 'outlier pixel removal' in image processing literature). Gauss, lowpass filter --------------------- The target pixel becomes the weighted average of the greyvalues of the nw,n,ne, w,mid,e, sw,s,se pixels with corresponding weigths : 1,2,1, 2,4,2, 1,2,1 (i.e. the sum DIV 16 is calculated for the middle pixel). Average, lowpass filter ----------------------- Weighted average, all weights equal to 1 (i.e. result is sum DIV 9). Laplace, highpass filter ------------------------ Weighted average, with weights 0,-1,0, -1,5,-1, 0,-1,0 (i.e. sum is calculated, and a range check is done (<0 becomes 0, >255 becomes 255)). Grad-x Sobel, highpass filter ----------------------------- Weighted average, with weights -1,0,1, -2,0,2, -1,0,1 (i.e. sum is calculated, 127 is added, and a range check is done). Grad-y Sobel, highpass filter ----------------------------- Weighted average, with weights -1,-2,-1, 0,0,0, 1,2,1 (calculation as under Grad-x Sobel filter). Maximum ------- The middle pixel becomes the maximum value of all nine pixels. Minimum ------- The middle pixel becomes the minimum value of all nine pixels. Sharpen (soft), highpass filter ------------------------------- Weighted average, with weights -1,-1,-1, -1,24,-1, -1,-1,-1 (i.e result is sum DIV 16, with range check). Sharpen (strong), highpass filter --------------------------------- Weighted average, with weights -1,-1,-1, -1,16,-1, -1,-1,-1 (i.e result is sum DIV 8, with range check). Lee, crispening filter ---------------------- For every pixel, either the local minimum or maximum, whichever is closest to the original. - Histogram equalization First, a 'cumulative histogram' is calculated that contains the cumulative frequencies of the greyvalues in the entire range (i.e. the cumulative value of greyvalue 255 is always equal to the total number of pixels in the image). The cumulative histogram is then scaled down and used as a transformation factor table to map the old greyvalue range to the full 0-255 greyvalue range. This yields a new cumulative histogram graph that is as 'flat' as possible, i.e. the greyvalue content of the image has been 'balanced'. ---------------- - Memory usage - ---------------- GreyEdit automatically grabs the memory it needs to load/grab an image, and releases it again when the image is discarded (i.e. the image window is closed or a new image is loaded/grabbed) or cut down. This ensures that it always runs in the minimum amount of memory and that you don't need to worry about how much memory to allocate to it. Users of 1Mb machines will appreciate this scheme, which enables larger images to be handled without trouble when multitasking with other applications. ------------------------ - Translator & Creator - ------------------------ These applications, which were also written by me, are essential companions to GreyEdit. Translator reads a very large number of (mainly foreign) graphics formats, and can perform colour processing, dithering, scaling, rotate, etc.. It outputs either sprite or Clear files. All graphic formats accepted by Translator may be converted to grey-scale Clear files (to be used as input for GreyEdit) by using the 'Black and white' and Clear output options. Creator creates a number of (mainly foreign) graphics formats, accepting Clear files and sprite files as input. It can create GIF, TIFF, AIM and PBMPlus formats at present. This enables you to port images to a large number of other computer platforms. Translator and Creator are available from the address mentioned below and are part of my shareware image processing package. ----------- - The end - ----------- This application is Shareware, and part of the image processing package consisting of !Translator, !Creator and !GreyEdit. I have put a lot of effort and time into these programs. Therefore, if you find any of them useful, I kindly ask you to register yourself as a user of these programs. The registration fee is just 35 dutch guilders. You will receive a free disc with the latest versions of Translator, Creator, GreyEdit, and most of my other applications. You may not use or have this software in your posession beyond a two-week trial period without registering. Services that offer software for download (BBSses, mail servers, ftp sites, etc.), and PD/Shareware libraries and the like, may *not* store this software without my approval. If you want to register, or if you have praise, complaints, comments, bugs(!), or anything else to offer me, do not hesitate to write to John Kortink Nutterbrink 31 7544 WJ Enschede The Netherlands or try email to john@dialis.hacktic.nl. Payment NOTE ------------ Payment in CASH ONLY PLEASE, in any currency, for the equivalent of 35 dutch guilders (England £10). The only exceptions may be (in order of preference) : a) A Eurocheque, for 35 dutch guilders, *with* pass-number on the back b) Postal exchange for 35 dutch guilders c) Any other form of payment, which gets charged by the bank, but which I'm happy to accept if I end up with 35 dutch guilders after bank charges. Typical bank charges are £8 on any non-a) payment. Updates NOTE ------------ If you want Translator or Creator to handle a new format, always send me full information, and several example files. For registered users, new versions of the applications are available from the same address : just send £1 to cover postage and a self-addressed envelope containing a formatted 3.5" disc. You will receive the latest versions. Discs will always be returned immediately, and will not be put 'on hold' awaiting new versions. NOTE : I will *not* send new versions to unregistered users. Ask yourself if you wouldn't be better off registering, if only to get new versions easily. Happy imaging !!! _______________________________________________________________________________ !!! NOTE !!! You may NOT change this application or use ANY part of it in other products without my approval. You may spread it freely (with *ALL* files included), but not for any profit. This software is provided 'as is'. Using it is entirely at your own risk. This application may NOT be distributed as an 'extra' in commercial products. You are kindly invited to contact me to discuss financial details, should you want to do so. _______________________________________________________________________________