One of the features in Inkscape is a tool for tracing a bitmap imageinto a <path> element for your SVG drawing. These short notesshould help you become acquainted with how it works.
Currently Inkscape employs the Potrace bitmap tracing engine (potrace.sourceforge.net) by Peter Selinger.In the future we expect to allow alternate tracing programs; for now, however, this finetool is more than sufficient for our needs.
Acorn is a raster graphic editor for macOS developed by August Mueller of Flying Meat Inc, based out of Mukilteo, Washington, United States. Acorn was first released on September 10, 2007 and was built upon the framework of a previous image editing application of Flying Meat Inc., FlySketch. Priced at $50, Acorn 3 is a full featured image editor with a lot of high-end features, including raw conversion, multiple layers, vector graphics. What’s not entirely clear is who it’s aimed at.
Keep in mind that the Tracer's purpose is not to reproduce an exact duplicate of theoriginal image; nor is it intended to produce a final product. No autotracer can dothat. What it does is give you a set of curves which you can use as a resource for yourdrawing.
Potrace interprets a black and white bitmap, and produces a set of curves. For Potrace,we currently have three types of input filters to convert from the raw image tosomething that Potrace can use.
Generally the more dark pixels in the intermediate bitmap, the more tracing that Potracewill perform. As the amount of tracing increases, more CPU time will be required, andthe <path> element will become much larger. It is suggested that the user experimentwith lighter intermediate images first, getting gradually darker to get the desiredproportion and complexity of the output path.
To use the tracer, load or import an image, select it,and select the Path⇒Trace Bitmap item, or Shift+Alt+B.
The user will see the three filter options available:
Brightness Cutoff
This merely uses the sum of the red, green and blue (or shades of gray) of a pixel as anindicator of whether it should be considered black or white. The threshold can be setfrom 0.0 (black) to 1.0 (white). The higher the threshold setting, the fewer the numberpixels that will be considered to be “white”, and the intermediate image withbecome darker.
Edge Detection
This uses the edge detection algorithm devised by J. Canny as a way of quickly findingisoclines of similar contrast. This will produce an intermediate bitmap that will lookless like the original image than does the result of Brightness Threshold, but willlikely provide curve information that would otherwise be ignored. The threshold settinghere (0.0 – 1.0) adjusts the brightness threshold of whether a pixel adjacent to acontrast edge will be included in the output. This setting can adjust the darkness orthickness of the edge in the output.
The result of this filter will produce an intermediate image that is very different fromthe other two, but is very useful indeed. Bitwig studio 1 3 8 – highly customizable audio daw. Instead of showing isoclines of brightness orcontrast, this will find edges where colors change, even at equal brightness andcontrast. The setting here, Number of Colors, decides how many output colors therewould be if the intermediate bitmap were in color. It then decides black/white onwhether the color has an even or odd index.
The user should try all three filters, and observe the different types of output fordifferent types of input images. There will always be an image where one works betterthan the others.
Bitmap Editor Windows 10
After tracing, it is also suggested that the user try Path⇒Simplify(Ctrl+L) on the output path to reduce the number of nodes. This canmake the output of Potrace much easier to edit. For example, here is a typical tracingof the Old Man Playing Guitar:
Note the enormous number of nodes in the path. After hitting Ctrl+L,this is a typical result:
The representation is a bit more approximate and rough, but the drawing is much simplerand easier to edit. Keep in mind that what you want is not an exact rendering of theimage, but a set of curves that you can use in your drawing.
Authors:Bulia Byak; Jonathan Leighton; Colin Marquardt; Nicolas Dufour; Gellért Gyuris
Header / footer design: Esteban Capella — 2019
Bitmap image editor.
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Acorn is a new image editor built with one goal in mind - simplicity. Fast, easy, and fluid, Acorn provides the options you'll need without any overhead. Acorn feels right, and won't drain your bank account.
Take screenshots using Acorn and edit them right away.
Chain together image filters to create stunning effects.
Layer based image editing, an industry standard.
Make new images and layers using your built-in iSight.
Easy image and canvas resizing, just by changing the size of your window.
Take advantage of every pixel of your monitor with full screen image editing.
Tablet sensitive for pressure strokes and using the tablet's eraser.
Vector shape and text layers.
Freeform, elliptical, rectangular, and magic wand selections.
Gradients.
Create and apply custom text styles.
Control opacity and blending modes for each layer.
Write plugins using the Python scripting language, as well as in Objective-C.
GPU powered. The same graphics card that makes your gaming experience smooth, helps Acorn fly through the toughest of graphics operations.
Note: Now requires OS X 10.10 or later.
Big New Stuff
The Shape Processor - Acorn has a really great new feature called 'Shape Processing'. Have you ever wanted to generate a bunch of new shapes, and then arrange them all in a circle and adjust that radius right on the canvas? What about taking all your shapes and re-ordering them from smallest to largest? What if you wanted to take all your shapes and randomly assign each one a new color, and then scatter them around the canvas in a billion different locations? What about pushing all the shapes on your layer out of the way of a giant circle?.. Well, now you can.. Shape Processors are filters for shape layers, which will move and tweak and generate and adjust shapes for you. And best of all, they are non-destructive and stackable (just like Acorn's filters). So you can add a bunch, tweak, save, close, and come back later if you change your mind.
Things that go snap - This is a lot more snapping going on now. Snap to Grid, guides, shapes in layers, other layers, selections, canvas bounds, etc. It was a complete rewrite, there are now global preferences available for fine tuning how you'd like it to work, and we even made those changeable per document.
Completely rewritten bitmap selection stuff - It's super accurate and works wonders with retina displays.
Non destructive Levels and Curves - Levels and Curves joins all the other non destructive filters- this is pretty awesome. You can use Levels and Curves on shape layers, even combine in the same filters list, tweaking both at the same time, and add a Curves filter multiple times to the same image. I have no idea why you'd do this, but it sounds fun.
PDF Import - When you open up a PDF, you can now choose the resolution, page, and background color of the PDF you are opening.
Crop tool improvements:
Pressing 'x' will now swap the aspect ratio of the current crop frame (if you have one that is, otherwise it'll swap the current back and foreground colors).
Pressing 'h' will toggle hiding the areas outside of your crop frame.
You can now rotate your image while making a crop.
Hundreds of minor bug fixes
We fixed hundreds of minor bugs. Bugs that built up over the years that very few people ever encountered, like 'the shortcut key for zooming in doesn't work when the keyboard layout is set to Dvorak - Qwerty ⌘'. So we fixed pretty much all of those. It took months and months of work, it was super boring and mind numbing and it was really hard to justify, and it made Acorn 5 super late. But we did it anyway, because something in us felt that software quality has been going downhill in general, and we sure as heck weren't going to let that happen to Acorn. So we took a long break from adding features and just fixed stuff.
And if you reported one of these bugs that was fixed in Acorn 5 and we haven't already sent you a license- let us know and we'll make you one. (See, another good reason to report any bugs you find- free stuff!).
More shape layer and bezier stuff:
New menu items - 'Shape > Bezier Stuff > Align Anchors to Pixels' and 'Align Anchors to Half Pixels' (the latter command shows up when you hold down the option key). This will align all the anchor points in your shape to the pixel grid (or half of it). This helps with making crisp lines for you bezier nuts out there.
You can now change the inner radius of star shapes. THIS IS AWESOME. It's actually quite flexible, and you can make some really neat star shapes (and did you know- you can change the number of points on your star using the View > Quick Config popover?).
New option to reset bezier control points under the Shape > Bezier Stuff menu
If you double click on an open bezier shape, it will signal to the shape that you would like to continue extending it. There's also the option to do this under the Shape > Bezier Stuff menu item.
You can temporarily toggle the 'snap to pixels' setting when moving a bezier anchor by holding down the control key while moving it with the mouse.
You can now invert the selection on shape layers.
The Shape Quick Config popover will now work when you don't have any shapes selected (and the settings you change will reflect on the next shape you make).
The contextual menu for the layers list has a new 'Rasterize Shape Layer' menu for use on shape layers.
You can now close a path when creating it by pressing the enter or return keys. Pressing the escape key will finish editing it as well, but keep it open.
You can now move multiple selected anchors in a bezier path with the arrow keys or mouse.
If you have the option 'auto select layers' turned off, a single click and drag in a shape layer will now move all the graphics without them needing to be selected first.
If you have a single text box selected and you press the enter key, Acorn will start editing it.
Holding the command key over a control point for resizing shapes will allow you to rotate it instead. I'm thinking of killing off the secret rotate handles outside shapes as well. Does anyone care?
Added Control-C as a way to select a color. This is awesome if you want to pick up on another color, but you're currently editing text and the 'i' key doesn't cut it.
Changed the modifier to move selected shapes by a half pixel to shift-option (from command-option).
New shortcuts to toggle the fill / stroke on selected shapes. Shift-F for fill, Shift-B for stroke.
New blend modes - Acorn now has a 'Pin Light' blend mode, as well as a 'Mask' blend mode. The Mask one is pretty awesome- it works just like a layer mask, white lets pixels through, black erases.
Support for Photoshop brushes - There's approximately 10 billion PS brushes available for download on the internet, and you can drag and drop one onto Acorn to import and make new brushes.
Speaking of brushes..
The Brush tool has now been renamed to the Paint tool. Because a bunch of other tools now use brushes, and it hopefully reduces confusion.
About those other changes I just mentioned. The clone, paint, smudge, dodge, burn, and other tools that had crappy brushes now each have their own unique brush that you can configure via the brush designer. So now you can have scatter for the clone tool. Or adjust flow and softness for the burn tool. Or turn pressure sensitivity on and off for the eraser. Etc.
Image metadata editing (aka, EXIF and IPTC, sitting in a tree) - Image metadata is now viewable and editable. Use the File > File Info… menu item to bring up the editor. While not everything is editable, lots of good things are. And this is new- so if there's something you'd like to see here, let us know!
New options in the Filter Palette having to do with selections:
'Blend with canvas selection', which is the old standard behavior when applying filters to the selection. Acorn will apply your filter(s) to the currently selected area in your bitmap, and then draw the results of that filter over your layer.
'Copy over canvas selection'. This option will apply your filters to the current selection, and then replace the pixels in your selected area with the results of the filter. So in this case, if the filter returns transparent pixels, your layer will become transparent in those areas.
'Ignore canvas selection'. This option will ignore the canvas selection, and work copy the result on top of your whole layer.
Miscellaneous new stuff
When using Web Export, there's a new option to save your image with or without a color profile. It defaults to yes.
Pressing 'b' while in crop mode will toggle the 'Keep crop bounds inside canvas' option.
When using the search field in the filter browser, searches will also look in the description for the filter as well as the name. This way searching for 'saturation' will return Color Controls and Vibrance, where before it would return nothing.
New filter! 'Redraw Layer'. Here's how it works- add a blur filter, then add a monotone filter, then add the redraw layer. Instant Drop Shadow Thing. It's great if you want to apply some filters and then have your original image draw on top of everything.
Another New Filter! 'Offset'. This will.. offset your image. COMBINE THIS WITH REDRAW LAYER. Add a monotone, add an offset, add the redraw, and tada- you've got instant solid color copy of your image, but in the background. Great for doing simple emboss operations.
What's This? Yet Another New Filter?!?! Yes, it's true. There's now 'Remove Color Cast' under the Color Adjustments, which will help you remove things like the pesky yellow tint that you'll get from lightbulbs when shooting photos indoors.
Holding down the option in the stroke / fill / etc text fields when using the up and down arrows will change the value by .1. (Holding shift will change the value by 10 btw).
You can now click the zoom scale field in the bottom window, and change the canvas zoom by typing in a new value. Holding down the command key while clicking it will scale the canvas to 100%
Pressing shift-x will swap which color well has the focus for receiving color changes (and did you know pressing x will swap the fill and stroke colors?).
If you have one or more anchors selected in a bezier path, the Shape > Bezier Stuff > Align Selected Anchors to Pixel menu item will appear. Hold down option to align to half pixel. This menu item is 'Align all Anchors to (Half) Pixels' normally.
All of Acorn's documentation and tutorials are now indexed for searching via the Help menu. Try it out, it's pretty awesome.
New undo / redo notifications in the canvas. You can turn this on and off in the preferences. For the beta this is turned on by default (shipping won't however). I'd like a little feedback on it if you have any, which is why I'm forcing it on everyone to start with.
128 Bits Per Component support. Super deep images. Because why not?
If you add a single image via the File > Add Images… menu item, and it doesn't fit on the canvas, Acorn will begin a scale and rotate transform for you, with the image automatically scaled to fit into the canvas. If you want to pop out of the scale, pressing the ESC key will end it.
Guides will now scale with image when resizing.
The Selection palette will now show the x,y coordinates of the current selection now. It'll also hide the labels and such when there is no selection.
You can now delete a brush by selecting it from the brush palette list, and holding down the option key.
You can now command click on a layer mask's thumbnail to make a selection out of that mask.
When opening multipage tiff files, Acorn will now expand the canvas size to the largest page in the tiff file.
New filter 'Alpha Multiply', which will multiple the alpha values of your pixels by a certain amount, which can be awesome when you want to sharpen up anti-aliased edges of circles and other shapes.
You can now commit a bitmap layer mask by holding down the option key and choosing the Layer > Apply Layer Mask menu item.
The Clone, Smudge, Dodge, and Burn tools all have opacity options now.
If you hold down the shift key when creating a new guide from the ruler, Acorn will now create a vertical ruler where it would have previously created a horizontal ruler (and vice versa).
You can now drag and drop gradients from the gradient preview onto a shape or bitmap layer to apply it.
Hidden feature: Pressing 'x' when the gradient tool is active will flip the gradient colors.
There's a new option in the Canvas Size sheet which allows you to move the canvas guides (or not) when resizing.
The Bevel filter now has a Scale option, which can add a bit of finesse to your bevel.
Changed Stuff
We killed the little swap width and height widget in the new document window. Instead, you can use the keyboard shortcut cmd-] or cmd-[ to have them swap (and the menu items Image > Rotate Canvas > 90° Clockwise / Counter-Clockwise also does the same thing).
Zooming with a trackpad is a bit more consistent.
Removed the quickmask and fullscreen buttons from the tools palette. The full screen became silly on 10.9 w/ every window getting that button too, and the quick mask seems out of place by itself there.
Hiding the cursor when you do a two finger scroll. There's a system bug (feature?) where the cursor will constantly flicker otherwise. It's annoying, so we'll be hiding the cursor till a real fix comes from Apple or I find a better workaround.
Got rid of the brushes in the Erase category of brushes, since the eraser tool now uses the same system and it was kind of pointless. ALSO- did you know you can convert a brush to an eraser at just by holding down the command and option keys and then drawing with it?
When using the system eyedropper to pick up a color on the canvas, it now takes the composite of the layers, instead of the first color on the top layer. If you want to pick up on a specific color (including alpha) from a single layer, use a drawing tool such as the paint tool, and hold down the option key to pick up the color.
If you press a keyboard shortcut while editing a field that takes a numerical value (for instance, the brush size field), Acorn will ignore the letter you typed, and instead choose the tool. Is this annoying? Is this odd? I don't know yet, but I'm going to try it for a bit.
When switching to the crop tool with the 'c' key, Acorn will no longer automatically put a crop on the canvas for you. However, if you liked the old behavior, you can press the 'c' key twice in less than half a second, and you'll get an auto-crop on the canvas.
New fussy pref to change the opacity of the crop tool mask when making a crop.
The way brushing works has been rewritten considerably. Colors are much more accurate now.
Generate Shapes has been moved to the Shape > Process menu.
Very very very slight (super tiny) change to the way star shapes are drawn. It's a bit more accurate now, because Gus learnt a thing or two about maths.
The Line tool (shortcut key ';') is now a specialized bezier path. We're thinking of removing it actually…
If you have the preference to listen for trackpad rotation gestures turned on, it takes a little bit more effort to pop into rotating your canvas (which is a good thing).
The gather palettes command does a much better job at resizing the windows when the display resolution changes to something smaller (or you move your palettes to a shorter window).
The gradient swatches now do a better job drawing when you've got the system scrollbar pref set to always show the scroller.
Layer styles now respect the canvas origin preferences.
Acorn will no longer ask to move itself to the Applications folder if there's a newer version already there.
Double clicking a thumbnail in the layers list palette will make a selection out of that layer.
The target click area for the fx widget in the layers list is now from top to bottom of the cell, instead of the little 'fx' bit. Sloppy pointer skills rejoice.
The Edit > Fill… command is a bit more precise when it comes to opacity percentages.
If there's a network error when trying to use the feedback window, Acorn will offer to send the report via your email client.
You can no longer insert new layers into locked groups.
You can no longer draw or alter a layer that's inside a locked group.
When taking a screenshot, each display now gets it own document.
The feedback window will now save its contents when you quit, and restore everything when you next launch.
When opening up ICNS and WebP images, Acorn will now place them into a new untitled document, instead of referencing the original file. Acorn doesn't save these file types natively, so referencing the original image causes confusion with various parts of Acorn.
No longer loading Python plugins. If you really miss them, and would like to bring them back while you transition away from them, paste the following line in Terminal.app:
No longer loading Quartz Composition filters. If you really miss them, and would like to bring them back while you transition away from them, paste the following line in Terminal.app:
Now showing a warning when you try and scale up an image to a very large size in Web Export.
Acorn does a better job at generating previews for filters which take textures (like Glass Distortion)
Copying a layer to the clipboard will now set the correct opacity if you have the layer's opacity set to something less than 100%.
Acorn does a better job at figuring out the bounds of your image when trimming.
The kerning slider now goes from -500 to +500.
Web Export now remembers the matte color option between uses.
Acorn does a better job of matching up the brush cursor size with the canvas when you have the cursor size embiggened in the Accessibility System Preferences.
When exporting an image, Acorn no longer warns you if your image is being saved without layers. It's an export, yea- you're original file is fine.
The tool palettes hide automatically when opening up a RAW image, since they pretty much only get in the way.
Pressing 'm' will no longer cycle through the selection tools, and will now only select the rectangle selection tool. However, shift-m will cycle through the selection tools as in previous versions of Acorn.
When applying gradients to selected shapes, Acorn will now hide the selection bounds. This is handy because it helps you see exactly what you're going to get.
Updated some of the built in brushes, and removed old crusty ones.
When drawing on a mask, Acorn now converts the current color to a shade between black and white (otherwise the mask would get splotches of color on it, which doesn't make too much sense for a mask).
Guides are now 2 pixels wide, because this makes more sense when you want a shape to line up with it on it's center, not it's edge (which will change depending on which direction you are aligning something from).
Smaller PNG files on web export if there's no alpha channel needed.
Acorn does a better job with selection edges and the free transform tool.
Changed up the wording for the pixel processing options. None, Generic, and Linear Light are the new options. Killed document. That's fine, nobody but Gus and the Core Image team actually understands what this is.