dither before rendering

mariusandra · mariusandra · commit 42cfce3668d1 · 2025-08-15T15:09:53.000+02:00
diff --git a/backend/app/drivers/devices.py b/backend/app/drivers/devices.py
@@ -13,6 +13,8 @@ def drivers_for_frame(frame: Frame) -> dict[str, Driver]:
         }
         if device == "pimoroni.inky_impression" or device == "pimoroni.inky_impression_7" or device == "pimoroni.inky_impression_13":
             device_drivers["gpioButton"] = DRIVERS["gpioButton"]
+        if device == "pimoroni.inky_impression_7" or device == "pimoroni.inky_impression_13":
+            device_drivers["inkyPython"].can_png = True
     elif device == "pimoroni.hyperpixel2r":
         device_drivers = {"inkyHyperPixel2r": DRIVERS["inkyHyperPixel2r"]}
     elif device == "framebuffer":
diff --git a/backend/app/drivers/drivers.py b/backend/app/drivers/drivers.py
@@ -17,6 +17,7 @@ class Driver:
         name="inkyPython",
         import_path="inkyPython/inkyPython",
         vendor_folder="inkyPython",
+        can_png=False, # will be set to true for the frames that support this
         can_render=True,
     ),
     "gpioButton": Driver(
diff --git a/frameos/src/drivers/inkyPython/inkyPython.nim b/frameos/src/drivers/inkyPython/inkyPython.nim
@@ -1,6 +1,7 @@
-import osproc, os, streams, pixie, json, options, strutils, strformat
+import osproc, os, streams, pixie, json, options, strutils, strformat, locks
 import frameos/types
 import frameos/utils/dither
+import frameos/utils/image
 
 type ScreenInfo* = object
   width*: int
@@ -16,6 +17,25 @@ type Driver* = ref object of FrameOSDriver
   lastImageData: seq[ColorRGBX]
   debug: bool
 
+var
+  lastPixelsLock: Lock
+  lastPixels: seq[uint8] = @[]
+  lastWidth: int
+  lastHeight: int
+
+proc setLastPixels*(image: seq[uint8], width: int, height: int) =
+  withLock lastPixelsLock:
+    lastPixels = image
+    lastWidth = width
+    lastHeight = height
+
+proc getLastPixels*(): seq[uint8] =
+  withLock lastPixelsLock:
+    result = lastPixels
+
+proc notifyImageAvailable*(self: Driver) =
+  self.logger.log(%*{"event": "render:dither", "info": "Dithered image available"})
+
 proc safeLog(logger: Logger, message: string): JsonNode =
   try:
     result = parseJson(message)
@@ -41,21 +61,6 @@ proc safeStartProcess*(cmd: string; args: seq[string] = @[];
 proc deviceArgs(dev: string): seq[string] =
   if dev.len > 0: @["--device", dev] else: @[]
 
-proc paletteArgs(p: PaletteConfig, device: string): seq[string] =
-  if p != nil and p.colors.len > 0:
-    let arr = newJArray()
-    for (r, g, b) in p.colors:
-      arr.add( %* [r, g, b])
-    @["--palette", $arr]
-  elif device == "pimoroni.inky_impression_7" or device == "pimoroni.inky_impression_13":
-    let arr = newJArray()
-    for (r, g, b) in spectra6ColorPalette:
-      if r < 256 and b < 256 and g < 256:
-        arr.add( %* [r, g, b])
-    @["--palette", $arr]
-  else:
-    @[]
-
 proc init*(frameOS: FrameOS): Driver =
   discard frameOS.logger.safeLog("Initializing Inky driver")
 
@@ -120,16 +125,39 @@ proc render*(self: Driver, image: Image) =
     discard self.logger.safeLog("Skipping render. Identical to last render.")
     return
   self.lastImageData = image.data
-  let imageData = image.encodeImage(BmpFormat)
+
+  var imageData: seq[uint8]
+  var extraArgs: seq[string] = @[]
+  if self.device == "pimoroni.inky_impression_7" or self.device == "pimoroni.inky_impression_13":
+    var palette: seq[(int, int, int)]
+    if self.palette != nil and self.palette.colors.len > 0:
+      let c = self.palette.colors
+      palette = @[
+        (c[0][0], c[0][1], c[0][2]),
+        (c[1][0], c[1][1], c[1][2]),
+        (c[2][0], c[2][1], c[2][2]),
+        (c[3][0], c[3][1], c[3][2]),
+        (999, 999, 999),
+        (c[4][0], c[4][1], c[4][2]),
+        (c[5][0], c[5][1], c[5][2]),
+      ]
+    else:
+      palette = spectra6ColorPalette
+    imageData = ditherPaletteIndexed(image, palette)
+    setLastPixels(imageData, image.width, image.height)
+    self.notifyImageAvailable()
+    extraArgs.add "--raw"
+  else:
+    imageData = cast[seq[uint8]](image.encodeImage(BmpFormat))
 
   let pOpt =
     if self.mode == "nixos":
       safeStartProcess("/nix/var/nix/profiles/system/sw/bin/inkyPython-run",
-                       deviceArgs(self.device) & paletteArgs(self.palette, self.device),
+                       deviceArgs(self.device) & extraArgs,
                        "/srv/frameos/vendor/inkyPython", self.logger)
     else:
       safeStartProcess("./env/bin/python3",
-                       @["run.py"] & deviceArgs(self.device) & paletteArgs(self.palette, self.device),
+                       @["run.py"] & deviceArgs(self.device) & extraArgs,
                        "/srv/frameos/vendor/inkyPython", self.logger)
 
   if pOpt.isNone:
@@ -186,3 +214,28 @@ proc render*(self: Driver, image: Image) =
     discard self.logger.safeLog(line)
 
   process.close()
+
+# Convert the rendered pixels to a PNG image. For accurate colors on the web.
+proc toPng*(rotate: int = 0): string =
+  let width = lastWidth
+  let height = lastHeight
+  var outputImage = newImage(width, height)
+
+  let pixels = getLastPixels()
+  if pixels.len == 0:
+    raise newException(Exception, "No render yet")
+  for y in 0 ..< height:
+    for x in 0 ..< width:
+      let index = y * width + x
+      let pixelIndex = index div 2
+      let pixelShift = (1 - (index mod 2)) * 4
+      let pixel = (pixels[pixelIndex] shr pixelShift) and 0x07
+      outputImage.data[index].r = spectra6ColorPalette[pixel][0].uint8
+      outputImage.data[index].g = spectra6ColorPalette[pixel][1].uint8
+      outputImage.data[index].b = spectra6ColorPalette[pixel][2].uint8
+      outputImage.data[index].a = 255
+
+  if rotate != 0:
+    return outputImage.rotateDegrees(rotate).encodeImage(PngFormat)
+
+  return outputImage.encodeImage(PngFormat)
diff --git a/frameos/vendor/inkyPython/run.py b/frameos/vendor/inkyPython/run.py
@@ -4,6 +4,7 @@
 import inspect
 import traceback
 import json
+import numpy
 from devices.util import log, init_inky, get_int_tuple
 
 def read_binary_data():
@@ -36,73 +37,78 @@ def parse_palette(palette_str):
 if __name__ == "__main__":
     parser = argparse.ArgumentParser(add_help=False)
     parser.add_argument("--device", default="")
-    parser.add_argument("--palette", default="")
+    parser.add_argument("--raw", action="store_true")
     args, _ = parser.parse_known_args()
 
     inky = init_inky(args.device)
     if not inky:
         sys.exit(1)
 
-    # If a palette is provided, override both palettes on the instance
-    if args.palette:
-        custom = parse_palette(args.palette)
-        if custom:
-            try:
-                inky.DESATURATED_PALETTE = custom
-                inky.SATURATED_PALETTE = custom
-                log({"message": "applying custom palette", "palette": custom})
-            except Exception as e:
-                log({"warning": f"failed to apply custom palette: {e}"})
-        else:
-            log({"warning": "invalid --palette format; ignoring"})
-    else:
-        log({"message": "no custom palette provided; using inky default"})
-
     resolution = getattr(inky, "resolution", (getattr(inky, "width", 0), getattr(inky, "height", 0)))
     width, height = get_int_tuple(resolution)
     colour = getattr(inky, "colour", getattr(inky, "color", None))
     log({ "inky": True, "width": width, "height": height, "color": colour })
 
     data = read_binary_data()
-    log({ "bytesReceived": len(data), "message": "rendering on eink display" })
+    log({ "bytesReceived": len(data), "format": "dithered" if args.raw else "rgb", "message": "rendering on eink display" })
 
-    try:
-        from PIL import Image
-    except ImportError:
-        log({ "error": "PIL python module not installed" })
-        sys.exit(1)
-
-    try:
-        image = Image.open(io.BytesIO(data))
-
-        set_image = getattr(inky, "set_image", None)
-        if not callable(set_image):
-            log({ "error": "inky.set_image() not available on this driver" })
+    if args.raw:
+        try:
+            expected = (width * height + 1) // 2
+            if len(data) != expected:
+                log({ "error": f"expected {expected} bytes, got {len(data)}" })
+                sys.exit(1)
+            arr = numpy.frombuffer(data, dtype=numpy.uint8)
+            buf = numpy.empty(width * height, dtype=numpy.uint8)
+            buf[0::2] = arr >> 4
+            buf[1::2] = arr & 0x0F
+            inky.buf = buf.reshape((height, width))
+            show = getattr(inky, "show", None)
+            if not callable(show):
+                log({ "error": "inky.show() not available on this driver" })
+                sys.exit(1)
+            show()
+        except Exception as e:
+            log({ "error": str(e), "stack": traceback.format_exc() })
+            sys.exit(1)
+    else:
+        try:
+            from PIL import Image
+        except ImportError:
+            log({ "error": "PIL python module not installed" })
             sys.exit(1)
 
-        # Try to match the signature len (1 or 2 params); fall back gracefully.
         try:
-            signature = inspect.signature(set_image)
-            if len(signature.parameters) == 2:
-                set_image(image, saturation=1)
-            elif len(signature.parameters) == 1:
-                set_image(image)
-            else:
-                log({ "error": f"inky.set_image() expects {len(signature.parameters)} params; only 1 or 2 supported" })
+            image = Image.open(io.BytesIO(data))
+
+            set_image = getattr(inky, "set_image", None)
+            if not callable(set_image):
+                log({ "error": "inky.set_image() not available on this driver" })
                 sys.exit(1)
-        except (ValueError, TypeError):
+
+            # Try to match the signature len (1 or 2 params); fall back gracefully.
             try:
-                set_image(image, saturation=1)
-            except TypeError:
-                set_image(image)
+                signature = inspect.signature(set_image)
+                if len(signature.parameters) == 2:
+                    set_image(image, saturation=1)
+                elif len(signature.parameters) == 1:
+                    set_image(image)
+                else:
+                    log({ "error": f"inky.set_image() expects {len(signature.parameters)} params; only 1 or 2 supported" })
+                    sys.exit(1)
+            except (ValueError, TypeError):
+                try:
+                    set_image(image, saturation=1)
+                except TypeError:
+                    set_image(image)
 
-        show = getattr(inky, "show", None)
-        if not callable(show):
-            log({ "error": "inky.show() not available on this driver" })
+            show = getattr(inky, "show", None)
+            if not callable(show):
+                log({ "error": "inky.show() not available on this driver" })
+                sys.exit(1)
+            show()
+        except Exception as e:
+            log({ "error": str(e), "stack": traceback.format_exc() })
             sys.exit(1)
-        show()
-    except Exception as e:
-        log({ "error": str(e), "stack": traceback.format_exc() })
-        sys.exit(1)
 
     sys.exit(0)

Original file line number	Diff line number	Diff line change
`@@ -13,6 +13,8 @@ def drivers_for_frame(frame: Frame) -> dict[str, Driver]:`
`13`	`13`	`}`
`14`	`14`	`if device == "pimoroni.inky_impression" or device == "pimoroni.inky_impression_7" or device == "pimoroni.inky_impression_13":`
`15`	`15`	`device_drivers["gpioButton"] = DRIVERS["gpioButton"]`
	`16`	`+ if device == "pimoroni.inky_impression_7" or device == "pimoroni.inky_impression_13":`
	`17`	`+ device_drivers["inkyPython"].can_png = True`
`16`	`18`	`elif device == "pimoroni.hyperpixel2r":`
`17`	`19`	`device_drivers = {"inkyHyperPixel2r": DRIVERS["inkyHyperPixel2r"]}`
`18`	`20`	`elif device == "framebuffer":`