INTRODUCTION

Welcome to ALBERT, the pixel art editor for creating extended Commodore 64 images. In case you were wondering, ALBERT was named after Albert Charpentier, one of the VIC-II designers. However, ALBERT is also an acronym that stands for “Advanced Lightweight Bitmap Extender with Raster Tech”.

ALBERT is a multi-platform cross-development pixel art editor, brought to you by Luigi Di Fraia (aka TCE – code and ideas) and Joachim Ljunggren (aka The Sarge – UI/UX, ideas, and testing). ALBERT allows its users to create Commodore 64 images that extend into the left and right borders of the visible screen, with sprites to display the extra pixels, using an uncomplicated drawing workflow, without requiring the assistance of a coder. ALBERT also allows its users to create standard images without using the borders.

Designs can be saved to project files for later modification. A project file mirrors ALBERT’s virtually unlimited undo/redo mechanism as it contains all work-stages. The latter can be exported to PNG files to produce a time-lapse and illustrate all production stages of the creative process behind a project, e.g. by using ffmpeg.

Currently ALBERT can convert non-native images (in PNG format), based on the Commodore 64 palette in use and using three different approaches:

• nearest color match,
• error diffusion (Floyd-Steinberg) dithering, or
• ordered (Bayer) dithering.

Furthermore, whereas the natural (Euclidean) distance is found to be unsuitable for color conversion, a weighted alternative is available. The latter should produce results in line with expectations based on the luminance value of Commodore 64 palette colors.

Finally, a curves adjustment widget is provided in order to adjust each color channel separately and/or all of them at the same time.

ALBERT also integrates with the programming language Lua, to expose a scripted drawing interface. The scripting window is used for this purpose, providing support for syntax highlighting, undo/redo, displaying line numbers, and other features typical of a source code editor.

AVAILABLE MODES

Bitmap + side borders (416×200 pixels)

This mode allows users to freely pixel onto the bitmap area and its side borders, subject to the usual restrictions for bitmaps and sprites. It is available in both multicolor and hires modes, each with its own limitations.

Bitmap only (320×200 pixels)

This mode allows users to pixel within the bitmap area, leaving the border areas inaccessible. It is also available in both multicolor and hires modes, again each with its own limitations.

MAIN WINDOW

TOOLBAR

Here are the tools for pixel manipulation: PEN, ERASER, FILL, EYEDROPPER, PAN TOOL, ROTATE CANVAS, and SELECTION TOOL.

COLORS

Depending on the selected mode, you can modify common sprite colors using the palette color boxes by setting SPRITE MC0 or SPRITE MC1. Similarly, you can set the BACKGROUND COLOR. In MULTICOLOR mode, each sprite has three colors, including an individual color. 

In HIRES mode, only the individual color can be set, and SPRITE MC0 or SPRITE MC1 are not displayed; only the BORDER COLOR is visible.

CANVAS

The canvas is divided into character (char) blocks and sprite blocks based on the selected mode. Char blocks are 8×8 pixels in size, while sprite blocks are 24×21 pixels in size.

In multicolor mode, each pixel is double the width of a pixel in Hires mode. Consequently, the pixels in a character block are 4×8 pixels.

Each char block can contain three colors and one background color.

In hires mode, each char block can have one foreground color and one background color.

Sprites operate differently, requiring the assignment of two global colors that all sprites will use, along with one individual color per sprite.

Side border mode imposes a limitation due to the hardware: rows 5-6 and rows 8-9 cannot use different individual colors; these two rows must have the same color. This limitation is illustrated by the lines outside the canvas connecting these rows.

In hires mode, due to the method used to avoid the color associated with the high nybble of the last character in a screen row from bleeding into the background, the last column of the screen area is not in use and sprites are positioned over it so that users can set pixels there.

Furthermore, due to the way the VIC-II hardware works, in hires mode black bleeds into the right border on raster line $32 and into the left border on raster line $33. For this reason, side borders are opened starting from raster line $33 instead of $32, the latter being what happens for multicolor mode. This lets users choose any border color that’s not just black, but results in the first rasterline in the left border being hidden on a Commodore 64 and therefore not editable in ALBERT.

Occasionally, the grid may be difficult to discern due to the color choices made in the artwork.

To toggle between a lighter and darker version of the grid, press the key “Z”.

BOTTOM STATUS BAR

This widget provides various status information, as detailed below.

MODE: Indicates the currently selected mode of operation.

ASPECT RATIO: Displays the aspect ratio in use. Refer to the corresponding section in this manual for further details.

BRUSH: Represents the brush size in pixels.

100% and Degree: Indicates the canvas zoom level and rotation in degrees.

CHAR: Displays the coordinates of the character your mouse pointer is hovering over.

SPRITE: Displays the coordinates of the sprite your mouse pointer is hovering over.

TOOLS

PEN (shortcut B)

This is the pixel pen. This tool allows you to set pixels on the canvas with varying brush sizes, ranging from 1 pixel in diameter to 24 pixels in diameter. While drawing, you can press the left mouse button to draw with the primary color or the right mouse button to draw with the secondary color.

The brush size can be adjusted by pressing the “,” or “.” keys, respectively. “,” decreases the brush size, while “.” increases the brush size. The keys “[“ and “]” provide the same adjustment.

The brush size is displayed in the status bar at the bottom of the canvas window.

Holding the SHIFT key after setting the first brush will transform the PEN TOOL into a rapid line tool, allowing you to preview the line while moving the cursor. Clicking on the canvas will set the line into the desired position.

ERASER (shortcut E)

This tool is designed to erase specific pixels on the canvas, thereby revealing the underlying background color of the current project.

FILL (shortcut G)

This tool fills a designated area with a selected color. You can use the left mouse button to fill with the primary color, or use the right mouse button to fill with the secondary color.

EYEDROPPER (shortcut ALT + left mouse button)

This tool captures the color of the pixel you select with a mouse click. This functionality can be utilized to set both primary or secondary color by pressing the left or right mouse button.

PAN CANVAS  (shortcut hold SPACE and drag mouse, or hold scroll wheel on mouse while dragging)

This tool performs unrestricted panning around the canvas, allowing you to concentrate on the specific area you are working on at any given time.

ROTATE CANVAS (shortcut R + mouse left mouse button)

This tool allows you to freely rotate the canvas angle. This can be particularly useful when attempting to create artwork at an unconventional angle, as it facilitates the execution of such tasks with greater ease.

By holding down the SHIFT key while dragging the canvas, you can snap the rotation angle to multiples of 22.5 degrees.

The canvas can also be rotated by holding down the R key and dragging the mouse.

SELECTION MARKER (shortcut M)

Utilizing this tool, you can freely draw a marker that snaps to a pixel level. Upon releasing the mouse button, you will be presented with a selected area that can be manipulated using the mouse or copied, pasted, and modified in new areas of the current project.

The selection can also be directly dragged around the canvas with real-time color clash calculations.

Pressing the ALT key before dragging of the selection starts makes it transparent where the background color is in use.

COLORS

PALETTE (shortcut 1-9, SHIFT + 1-8)

This area on the toolbar shows the 16 colors the Commodore 64 VIC-II chip can display.

You can assign two colors from this palette to your pixel pen. Clicking on the palette with your left mouse button sets the primary color. This is shown by a white frame marking the color box. Clicking on a color with your right mouse button sets the secondary color. This is shown with a dot on the color box.

SPRITE COLORS AND BACKGROUND/BORDER COLOR

Depending on whether you are working on a project with sprites in the border or using only the standard bitmap mode, the toolbar will display the color boxes that are applicable to the selected mode.

You set colors by selecting the color of your choice from one of the boxes in the palette and then clicking on the “Background”, “Border”, “Sprite MC0”, or “Sprite MC1” color boxes.

In the “Bitmap + sprites” multicolor mode, you are allowed to set two global colors for the sprites. These two colors will be applied to all sprites in the borders. Each sprite can have one distinct color unique to that sprite. This is set by painting with the pixel pen or filling.

However, there are exceptions to this rule, which are illustrated on the canvas with the lines connecting sprite rows 5 and 6, and rows 8 and 9 together. In these cases, sprites on the same column must share the same individual color. This is due to inner workings of the VIC-II chip.

MENUS

FILE

NEW… (shortcut CTRL/CMD + N)

Creates a new project. The mode chooser dialog window is shown, where you can select presets of your choice. Options include sprites in the borders and standard bitmap canvases without any enhancements.

In this dialog window, you can also set the background color and sprite colors before creating the project. These settings can be modified with the available color tools at any time.

OPEN… (shortcut O)

Opens a project file.

OPEN RECENT

This menu item displays up to ten most recently saved or opened project files for ease of access. At the bottom of the list, there is an option to clear the list.

SAVE (shortcut S)

This menu item overwrites an existing project file with the current version.

SAVE AS…

This feature allows you to create a new copy of your project and provides the option to select a name and location for the file.

IMPORT IMAGE…

This feature imports images. Supported formats are:

For hires:

• Art Studio 1.x
• Doodle
• Image System
• Interpaint Hires

For multicolor:

• Advanced Art Studio
• Blazing Paddles
• Koala Painter 2
• Vidcom 64
• Wigmore Artist 64

These image formats are all bitmap images without any sprites in the borders.

IMPORT SPRITES…

This feature imports sprites, which will appear in the side borders. Supported file formats are PRG and PMAP.

The sprites must be arranged in four columns by ten rows for ALBERT to place them correctly. Two columns for the left side and two columns for the right side.

IMPORT REFERENCE IMAGE…

This feature allows you to import an image as a reference overlay on top of their canvas. This image is not part of the actual pixel work and cannot be modified or erased. Additionally, it does not cause color clashes. Its primary purpose is to serve as a transparent image with line art acting as a guide for you to paint below the reference image.

The reference image can be enabled or disabled in the menu under VIEW/SHOW (or HIDE) REFERENCE IMAGE.

CONVERT IMAGE…

This feature allows you to import a complete image and automatically convert it into bitmap, optionally with sprites in the borders. The image must be in PNG format with a 24-bit or 32-bit color depth.
If you select the “Bitmap + side borders” mode, the image must have a resolution of 416×200 pixels.
If you select the “Bitmap only” mode, the image must have a resolution of 320×200 pixels.

Upon selecting an appropriate image, a dialog window will be displayed, allowing you to manipulate the resulting image in real time. This visualization demonstrates the conversion to 16 colors and the application of the relevant color clash algorithms.

A palette can be chosen, as each palette yields distinct conversion outcomes.

The histogram displays the color distribution of the image from darkest to left to brightest to right. The curve overlay provides you with the ability to alter how different exposure areas are handled. This can be achieved on an RGB level or individually for Red, Green, or Blue channels. You can create new adjustment points by clicking on the histogram area, which helps you to fine tune adjustment curves. To remove a point from the curve, you can drag it outside of the histogram area until it’s removed.

Dithering can be set to NONE, ERROR DIFFUSION, or ORDERED. Each setting yields distinct conversion results. NONE does not apply any dithering algorithm to the image and may be suitable if you imported a sketch you intend to continue working on and maintain a clean image. ERROR DIFFUSION and ORDERED introduce dithering to the image. Depending on your preference, one or the other may yield the desired result. None of these algorithms achieves the quality of a manual and personalized style, and this should be viewed as a rapid conversion tool rather than a means of producing a final image.

In the “Bitmap + sprites” mode, MC0 and MC1 are global sprite colors. It is crucial to select a suitable option at this stage that yields favorable results for your image. After converting the image by clicking “OK,” the data from the original image is irrevocably lost and cannot be recovered by modifying other sprite color globals that may have produced better outcomes.

BG represents the background color.

COLOR DISTANCE can be set to NATURAL or WEIGHTED. These settings may yield different results for your image, depending on the exposure. WEIGHTED tends to produce more colorful outcomes.

LOGARITHMIC SCALE redistributes color intensities, enabling better visualisation of underrepresented tonal regions.

The RESET CURVES button resets the adjustment curves in the histogram area, allowing you to start anew if your work has not been satisfactory.

EXPORT TO IMAGE AS…

Save a PNG image of your work to a location and name of your choice.

The export options available depend on the mode you are working in. If you are working in “Bitmap + sprites” mode, the only option is to export to the PNG format. However, if you are working in the “Bitmap only” mode, several options are available to you.

Exporting to PNG with or without the border added to the image.

Exporting to the native Koala Painter format if you are working in multicolor mode.

Exporting to the native Art Studio format if you are working in hires mode.

EXPORT TO ULTIMATE DEVICE (shortcut E)

This feature allows you to transmit a snapshot of the canvas to an Ultimate device, such as a Ultimate64 or a C64, equipped with an Ultimate1541 cartridge, if they are accessible on your local network. To facilitate this process, you must ensure that the correct IP address of your Ultimate device is configured in the Settings/Preferences section of ALBERT.

This functionality proves particularly useful for swiftly evaluating the visual appearance of your work on actual hardware. Additionally, if your Ultimate device is connected to a CRT screen, it allows you to assess the pixel art on the C64 in its entirety.

EXPORT TO PRG FILE AS…

This feature constructs and Exomize’s a PRG executable file of your work. This PRG file can be executed on a standard C64. This is the prevalent file format for standalone graphic releases on the C64, which renders you independent of a programmer to finalize your work.

SAVE WORKSTAGES…

ALBERT saves all the progress of your work in project files. Consequently, ALB files tend to become quite large by C64 standards. With this tool, you can export out each mouse click you have ever made on the image you are working on. After selecting a folder where to store the files, ALBERT generates a PNG sequence of every step. This process may take some time, especially if your image has a significant number of steps. It is not uncommon to encounter project files with up to 15,000 steps.

Once the export is complete, you can convert this PNG sequence into a movie file of your choice using an external tool. This feature is particularly useful for creating comprehensive timelapses to showcase or demonstrate your work.

EDIT

UNDO

This action reverses the most recent modification to your work. ALBERT provides an undo feature that allows you to revert to any previous state, up to the very first edit that you made for the current project.

REDO

This action redoes the action you last undid using the UNDO feature.

CLEAR HISTORY

This action completely erases all the recorded clicks you have made in ALBERT from the beginning of your work. This could be beneficial if you intend to send the ALB file to a third party, but without the history. The file size should be reduced to approximately 8-10 KiB.

However, be cautious, as if you save over your original file after clearing the history, all stages will be lost and cannot be retrieved.

CUT

This action eliminates the selected image area and transfers it to ALBERT’s internal clipboard.

COPY

This action copies the selected image area to ALBERT’s internal clipboard.

PASTE

Utilize this feature to paste a floating area from ALBERT’s internal clipboard onto the canvas. This floating area can be moved around with real-time calculations of color clashes. Once you are satisfied with the position, click the left mouse button to set it permanently on the canvas.

PASTE WITH TRANSPARENCY

Paste a floating area from ALBERT’s internal clipboard onto the canvas with a transparent background. If you copied an area that showed parts of the background, this area is considered transparent. This floating area can be moved around with real-time calculations of color clashes. When you are satisfied with the position, click the left mouse button to set it onto the canvas.

Pasting with transparency is very useful if you are copying and pasting round objects close to each other, as it will not overwrite the artwork below with the background color.

SELECT ALL

This action selects the entire canvas.

SELECT NONE

This action deactivates your selection.

TRANSFORM -> FLIP HORIZONTALLY (shortcut CTRL/CMD + J)

This action horizontally flips the selected area, or the whole canvas if no selection is active.

TRANSFORM -> FLIP VERTICALLY (shortcut CTRL/CMD + K)

This action vertically flips the selected area, or the whole canvas if no selection is active.

IMAGE

PALETTE

You have the option to select one of several versions of the C64 palette. This is your personal preference for what you believe are the correct colors on the C64.

The available palettes are PIXCEN, PEPTO, COLODORE, CCS64, PC64, VICE, JAMPAL, DEEKAY, and HIGH CONTRAST.

This does not modify the color data itself; it only affects their visual appearance.

ASPECT RATIO

Here, you can configure how the pixels appear while using different video standards. PAL and NTSC do not have square pixels. PAL pixels are slightly higher, resulting in an aspect ratio of 0.9375, instead of 1. NTSC has even higher pixels with an aspect ratio of 0.75. This affects both the drawing canvas and the Preview window.

This emulates how the image will appear on a CRT screen with a PAL or NTSC system. If you have created numerous circles in your artwork, this is something to consider because on PAL and NTSC, those circles appear more oval than circular. Therefore, you must strive to find a suitable compromise to ensure compatibility across various platforms. Modern TVs and monitors use an aspect ratio of 1:1 pixels, which are perfectly square and do not cause any stretching.

FILTER

NEAREST or BILINEAR are the two available filtering options. NEAREST disables any blurring effect on the canvas, while BILINEAR smooths images by interpolating pixel values, reducing jagged edges.

In contemporary workflow, it is advisable to maintain the NEAREST filter and enable CRT emulation in the Preview window.

COLOR SWAP

This tool facilitates the exchange of colors on a canvas. To utilize it, set the primary color to the desired replacement color and the secondary color to the color to be replaced. For instance, if you wish to swap blue in your artwork to red, set the primary color to red and the secondary color to blue. Subsequently, select “IMAGE/SWAP COLOR” from the menu. You can repeat this process to explore different color combinations and determine the most suitable option.

Note that if a selection is active, then this tool will only affect the selection.

COLOR REPLACE

This tool is analogous to COLOR SWAP, except that it replaces the color instead of swapping it. The process is the same, but you cannot revert to the original color unless you use the UNDO feature.

PIXEL PERFECT

This toggle determines whether ALBERT should be lenient when drawing freely with the mouse or more strict when setting pixels. When moving from pixel to pixel, the lenient method (PIXEL PERFECT OFF) enables slightly wider strokes because adjacent pixels will be set. Conversely, PIXEL PERFECT ON is more stringent when drawing freely, preventing stray pixels from being set, resulting in cleaner strokes.

SYMMETRY DRAW

This mode enables real-time mirroring of your brush strokes, producing symmetrical designs effortlessly.

NONE is the default mode and does not mirror your brush strokes.

HORIZONTAL mirrors your brush strokes on either side of the horizontal line that splits the canvas into an upper and lower half.

VERTICAL mirrors your brush strokes on either side of the vertical line that splits the canvas into a left and right half.

QUADRANT splits the canvas horizontally and vertically, mirroring your brush strokes to the three other areas.

BI-QUADRANT similar to QUADRANT but each area is further split into two partitions diagonally, with the splitting diagonal serving as an additional axis of symmetry.

KALEIDOSCOPE replicates drawing across eight axes of symmetry.

Green lines drawn on the canvas serve as a visual guide for indicating the locations of the mirroring. In Kaleidoscope mode axes of symmetry are drawn in yellow.

PAREIDOLIA

This tool generates a random pattern of circles and squares in various colors. It can be particularly useful when you are experiencing writer’s block or lack inspiration for a drawing. Within this seemingly random pattern, there may lie your next great idea, waiting to be discovered.

VIEW

ZOOM 1:1 (shortcut CTRL/CMD + 0)

Restores the image to its original, unzoomed state, wherein each pixel on the canvas corresponds to a single pixel on the monitor.

BEST FIT (shortcut CTRL/CMD + PG UP)

Maximizes the canvas to utilize the window’s size optimally, filling it to its full extent.

ZOOM IN (shortcut CTRL/CMD + + or MOUSE SCROLL WHEEL)

Increases the magnification of the canvas by a factor of 100%.

ZOOM OUT (shortcut CTRL/CMD + – or MOUSE SCROLL WHEEL)

Reduces the magnification of the canvas by a factor of 50%.

RESET CANVAS ROTATION (shortcut SHIFT + CTRL/CMD + R)

Resets the canvas rotation if rotated by the Rotate Canvas tool.

HIDE/SHOW REFERENCE GRIDS

This either reveals or conceals the character, sprite, and symmetry grids from your canvas.

HIDE/SHOW REFERENCE IMAGE

This feature either displays or conceals the reference image that was imported using the IMPORT REFERENCE IMAGE feature. Please refer to the corresponding section for further details on this tool.

HIDE/SHOW PREVIEW WINDOW

This either displays or conceals the Preview window. The Preview window is a supplementary window that displays the canvas at a different zoom level, which can be adjusted by zooming with the mouse scroll wheel. This window is devoid of distracting reference grids and strives to replicate the exact appearance of the image when executed in an emulator or on actual hardware.

Right-clicking on the Preview window presents a context menu that allows you to make the Preview window remain on top of all open windows on your system or behave similarly to any other windows.

CRT Emulation can be enabled to emulate the appearance of a CRT monitor, providing a visual representation of how your artwork may look on a CRT display.

HIDE/SHOW SCRIPTING WINDOW

This either displays or conceals the Scripting window. Using ALBERT’s scripting engine, you can write scripts to build images directly from code, eliminating the need for manual pixel manipulation. This allows you to create a wide range of content, from still images to animations that can be exported as PNG sequences.

The scripting engine can be used to draw lines, boxes, circles, and ovals, providing an exceptionally powerful toolset for image creation.

Available functions along with their description are provided below:

drawclear (): clears the canvas using the current background color

drawfill (pos_x, pos_y, color): flood fills starting at the given coordinates

drawbrush (pos_x, pos_y, color): draws a brush at the given coordinates

drawline (from_x, from_y, to_x, to_y, color): draws a line with width 1 connecting the given coordinates

drawrect (pos_x, pos_y, width, height, color): draws a hollow rectangle with line width 1, upper left corner at the given coordinates, and the given extents

drawrectf (pos_x, pos_y, width, height, color): draws a filled rectangle with upper left corner at the given coordinates and the given extents

drawcircle (center_x, center_y, radius, color): draws a hollow circle with line width 1, the given radius, and centered at the given coordinates

drawcirclef (center_x, center_y, radius, color): draws a filled circle with the given radius and centered at the given coordinates

drawellipse (center_x, center_y, radius_x, radius_y, color): draws a hollow ellipse with line width 1, given radiuses, and centered at the given coordinates

drawellipsef (center_x, center_y, radius_x, radius_y, color): draws a filled circle with given radiuses centered at the given coordinates

drawstar (top_left_x, top_left_y, width, color): draws a hollow star

brushsize (size): sets brush size; valid values are 1 through 24

checkpointon (): enables the creation of checkpoints in the history of changes after a drawing operation, if it modifies the contents of the canvas

checkpointoff (): disables the creation of checkpoints in the history of changes after a drawing operation

checkpointsave (): creates a checkpoint in the history of changes, which is useful to compound multile drawing operations in a single checkpoint while checkpointing is globally disabled

exportpng (full_path[, include_borders=true]): saves the contents of the canvas to a PNG image, optionally excluding borders for non-extended modes

invalidateon (): enables the automatic refresh of the canvas display after a drawing operation, if it modifies the contents of the canvas

invalidateoff (): disables the automatic refresh of the canvas display after a drawing operation

drawrefresh (): causes a refresh of the canvas display

bgcolor (color): replaces the background color

bordercolor (color): replaces the border color in non-extended multicolor mode and all hires modes

mcspritecolors (color_1, color_2): replaces common multi-color sprite colors in multicolor mode

SHOW PROPERTIES

This dialog window displays the cumulative number of changes you made since commencing your work on the current project.

The number of colors utilized in your artwork is indicated here.

Additionally, this dialog window provides information regarding the memory consumption of your image within your system.

Furthermore, it records the date and time when you commenced working on this artwork and the date and time of your most recent modifications.

SETTINGS/PREFERENCES

GENERAL

Invert Scroll Wheel Direction for Zooming

This preference allows you to reverse the behaviour of the scroll wheel when zooming.

Bind Zoom to Canvas

This feature makes sure that wherever the mouse pointer is when zooming, at least one edge of the drawable area stays in shot.

LUA SCRIPTING

Max Instruction Count

This value represents the number of Lua instructions that can be executed before the script interpreter yields, which is required to avoid infinite loops.

Font Settings

This dialog window allows you to select the font face and size to be used for ALBERT’s scripting window.

SPRITES

Attribute Byte Format

Ignore: Disregards the sprite color information that might be present in unused sprite data. 

Sprite Pad

Reads individual sprite colors from unused sprite data, according to the format defined in Sprite Pad.

ULTIMATE DEVICE

Host

The IP address of the Ultimate device, which is essential for transmitting artwork to the Ultimate device.

Timeout

In seconds. This value is used to define the maximum amount of time ALBERT will wait for a transmission operation to complete before aborting it. Depending on your network’s speed, you may need to extend this timeout.

The default timeout value is 2.5 seconds.

HELP

DOCUMENTATION

This manual is also available for offline reading. If you do not have Internet access to the official manual, we have provided a fallback version that can be accessed by pressing SHIFT + CMD + D on macOS and by holding down the CTRL key upon clicking on the DOCUMENTATION menu item on other systems.

KEYBOARD SHORTCUTS

The available key shortcuts, which are not already menu item accelerators, are detailed below:

Keys 1-8 (optionally with a Shift key pressed for some keyboard layouts): set color for the pen associated to the left mouse button

Keys , and .: decrease and increase brush size for freehand drawing

Keys [ and ]: decrease and increase brush size for freehand drawing

Key b: activates the pen tool

Key e: activates the erase tool

Key g: activates the flood fill tool

Key space: activates the pan tool, until released; left click and drag the canvas around to move it while active

Key r: activates the rotation tool, until released; left click and drag the canvas around to rotate it while active

Key Alt (left): temporarily activates the color picker tool if it makes sense based on the currently active tool (pen, erase, fill, pan)

Key Shift (left or right): enables multiline mode if the pen tool is active or snaps the rotation angle by the nearest multiple of 15 degrees if the rotation tool is active (r key)

Key z: when reference grids are active, press it to switch their color between two different shades of grey and improve cell grid visibility

Key Shift (left or right) + z: when reference grids are active, press both to toggle the pixel grid on and off

Key Delete: deletes the currently selected region, if one is active

Key Escape: disables the current selection, if one is active

Cursor Keys: translate the canvas

Key Tab: toggle the CRT emulation filter for the preview window