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lua-scripts-w-api/examples/ai_denoise.lua

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Lua

--[[
This file is part of darktable,
copyright (c) 2026 darktable developers.
darktable is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
darktable is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with darktable. If not, see <http://www.gnu.org/licenses/>.
]]
--[[
ai_denoise - example script demonstrating the darktable.ai Lua
API by denoising the selected images with tile-based inference.
Adds an "AI denoise" panel to the lighttable right column with a
"denoise selected" button. Each selected image is loaded through
the develop pipeline (so denoise sees the output of all enabled
IOPs, not the original raw), run tile-by-tile through the active
denoise model, and saved as a 16-bit TIFF grouped with the source.
Demonstrates:
* model lookup via dt.ai.model_for_task
* tensor crop/paste for tile-based inference
* linear <-> sRGB conversion (NR models train on gamma input)
* edge-replicated padding to suppress border artifacts
* background job with progress bar and cancellation
LIMITATIONS
* Image must be at least TILE_SIZE x TILE_SIZE (768 x 768 for
denoise-nind / denoise-nafnet); smaller inputs return an error.
* If a save fails mid-batch the Lua error propagates and aborts
the whole job. Wrap denoise_one in pcall if you need
batch-robust behaviour.
ADDITIONAL SOFTWARE NEEDED FOR THIS SCRIPT
* a denoise model enabled in preferences -> AI (denoise-nind,
denoise-nafnet, ...)
USAGE
* require this script from your luarc
* select one or more images in lighttable
* click the "denoise selected" button in the AI denoise panel
BUGS, COMMENTS, SUGGESTIONS
* file an issue on https://github.com/darktable-org/darktable
CHANGES
]]
local dt = require "darktable"
-- - - - - - - - - - - - - - - - - - - - - - - -
-- C O N S T A N T S
-- - - - - - - - - - - - - - - - - - - - - - - -
local MODULE_NAME = "ai_denoise"
-- darktable's NR models use static-shape ONNX: each model has a fixed
-- input dimension baked in at training time. The Lua API doesn't
-- expose this, so keep TILE_SIZE in sync with the model's
-- `attributes.input_sizes` in its config.json.
local TILE_SIZE = 768 -- denoise-nind, denoise-nafnet
-- overlap between adjacent tiles. larger values produce smoother
-- seams at the cost of more compute per pixel
local OVERLAP = 64
-- - - - - - - - - - - - - - - - - - - - - - - -
-- F U N C T I O N S
-- - - - - - - - - - - - - - - - - - - - - - - -
-- Surround the input with `pad` pixels on every side, replicating the
-- outermost rows/columns ("edge clamp" padding). Boundary tiles then
-- see plausible context instead of a literal image edge, so the
-- network's internal zero-padding no longer leaks into the visible
-- output as colour artifacts along the image rim.
local function pad_replicate(input, pad)
local C = input:shape()[2]
local H = input:shape()[3]
local W = input:shape()[4]
local padded = dt.ai.create_tensor({1, C, H + 2 * pad, W + 2 * pad})
-- center: original image
padded:paste(input, pad, pad)
-- left and right strips: replicate first / last column of input
local left_col = input:crop(0, 0, H, 1)
local right_col = input:crop(0, W - 1, H, 1)
for i = 0, pad - 1 do
padded:paste(left_col, pad, i)
padded:paste(right_col, pad, pad + W + i)
end
-- top and bottom strips: replicate first / last row of the already
-- horizontally-padded buffer so the four corners get filled correctly
local top_row = padded:crop(pad, 0, 1, W + 2 * pad)
local bottom_row = padded:crop(pad + H - 1, 0, 1, W + 2 * pad)
for i = 0, pad - 1 do
padded:paste(top_row, i, 0)
padded:paste(bottom_row, pad + H + i, 0)
end
return padded
end
-- Tile a [1,C,H,W] tensor through the model with overlap-blended seams.
-- Each tile is tile_size x tile_size, successive tiles step by
-- (tile_size - 2*overlap), and only the central (non-overlap) region
-- of each tile is pasted into the output. Image-boundary edges keep
-- their full extent; only image-interior seams drop the overlap margin.
--
-- The trailing tile in each axis is pinned to the image boundary so
-- the residual right/bottom strip is never smaller than 2*overlap --
-- otherwise it would have to be skipped (the model has a fixed input
-- size) and those pixels would never be written.
local function run_tiled(ctx, input, tile_size, overlap,
job, base_pct, span_pct)
local C = input:shape()[2]
local H = input:shape()[3]
local W = input:shape()[4]
if H < tile_size or W < tile_size then
return nil, string.format("image too small (%dx%d) for tile %d",
W, H, tile_size)
end
local step = tile_size - 2 * overlap
-- enumerate tile origins along one axis, ending exactly at the boundary
local function origins(extent)
local out, p = {}, 0
while p + tile_size < extent do
out[#out + 1] = p
p = p + step
end
out[#out + 1] = math.max(0, extent - tile_size)
return out
end
local ys, xs = origins(H), origins(W)
local total = #xs * #ys
local output = dt.ai.create_tensor({1, C, H, W})
local done = 0
for _, ty in ipairs(ys) do
for _, tx in ipairs(xs) do
if job and not job.valid then return nil, "cancelled" end
local tile_in = input:crop(ty, tx, tile_size, tile_size)
local tile_out = ctx:run(tile_in)
-- central region to keep: drop overlap on every inner edge;
-- full extent at image-boundary edges
local at_top = (ty == 0)
local at_left = (tx == 0)
local at_bottom = (ty + tile_size >= H)
local at_right = (tx + tile_size >= W)
local cy = at_top and 0 or overlap
local cx = at_left and 0 or overlap
local ch = tile_size - cy - (at_bottom and 0 or overlap)
local cw = tile_size - cx - (at_right and 0 or overlap)
output:paste(tile_out:crop(cy, cx, ch, cw), ty + cy, tx + cx)
done = done + 1
if job then
job.percent = base_pct + span_pct * (done / total)
end
end
end
return output
end
-- Denoise one image: load through the develop pipeline, run tiled
-- inference, save as 16-bit TIFF, group with the source.
local function denoise_one(ctx, img, tile_size, job, base_pct, span_pct)
-- darktable returns the develop-pipeline output as scene-linear RGB;
-- the NR models were trained on sRGB-gamma input, so we re-encode
-- before inference and decode back to linear before saving
local input = dt.ai.load_image(img)
if not input then return false, "load_image failed" end
input:linear_to_srgb()
-- pad so the image's outer rim is no longer at a tile boundary;
-- the padded strip absorbs the network's edge artifacts and gets
-- cropped away after inference
local H = input:shape()[3]
local W = input:shape()[4]
local padded_in = pad_replicate(input, OVERLAP)
local padded_out, err = run_tiled(ctx, padded_in, tile_size, OVERLAP,
job, base_pct, span_pct)
if not padded_out then return false, err end
local output = padded_out:crop(OVERLAP, OVERLAP, H, W)
output:srgb_to_linear()
local base = img.filename:match("(.+)%..+$") or img.filename
local out_path = img.path .. "/" .. base .. "_denoised.tif"
output:save_tiff(out_path, 16, img)
-- import the result and group with the source so they live together
-- in the lighttable
local imported = dt.database.import(out_path)
if imported then imported:group_with(img) end
return true
end
-- Button handler: looks up the active denoise model, fans out the
-- selected images, and reports progress via a cancellable job.
local function process_denoise()
local model_id = dt.ai.model_for_task("denoise")
if not model_id then
dt.print("no denoise model enabled -- pick one in preferences -> AI")
return
end
local images = dt.gui.selection()
if #images == 0 then
dt.print("select at least one image")
return
end
-- progress + cancel job. the cancel callback flips job.valid; the
-- main loop polls it between tiles to stop cleanly
local job = dt.gui.create_job(
string.format("AI denoise (%d image%s)",
#images, #images == 1 and "" or "s"),
true,
function(j) j.valid = false end)
dt.print_log(string.format(
"[ai_denoise] starting: %d image%s with model %s",
#images, #images == 1 and "" or "s", model_id))
local t_start = os.time()
local ctx = dt.ai.load_model(model_id)
if not ctx then
dt.print("failed to load model: " .. model_id)
job.valid = false
return
end
local span = 1.0 / #images
local done = 0
for i, img in ipairs(images) do
if not job.valid then break end
dt.print_log(string.format("[ai_denoise] [%d/%d] %s",
i, #images, img.filename))
local ok, err = denoise_one(ctx, img, TILE_SIZE, job,
(i - 1) * span, span)
if not ok then
dt.print(string.format("[%d/%d] %s: %s",
i, #images, img.filename, tostring(err)))
dt.print_log(string.format("[ai_denoise] [%d/%d] %s FAILED: %s",
i, #images, img.filename, tostring(err)))
else
done = done + 1
end
end
ctx:close()
job.valid = false
local elapsed = os.time() - t_start
dt.print(string.format("denoise complete: %d image%s",
#images, #images == 1 and "" or "s"))
dt.print_log(string.format(
"[ai_denoise] finished: %d/%d in %ds",
done, #images, elapsed))
end
-- script_manager integration: called when the user disables the script.
-- darktable can't remove a registered lib from the UI at runtime, so we
-- only stop any in-flight work; the panel itself remains until restart.
local function destroy()
-- nothing persistent to clean up: each click runs its own job and
-- closes its own model context
end
-- - - - - - - - - - - - - - - - - - - - - - - -
-- M A I N
-- - - - - - - - - - - - - - - - - - - - - - - -
dt.register_lib(
MODULE_NAME, -- plugin id
"AI denoise", -- displayed name
true, -- expandable
false, -- no reset button
{[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_RIGHT_CENTER", 100}},
dt.new_widget("box") {
orientation = "vertical",
dt.new_widget("button") {
label = "denoise selected",
clicked_callback = process_denoise,
}
},
nil, nil
)
-- - - - - - - - - - - - - - - - - - - - - - - -
-- S C R I P T M A N A G E R I N T E G R A T I O N
-- - - - - - - - - - - - - - - - - - - - - - - -
local script_data = {}
script_data.metadata = {
name = "AI denoise",
purpose = "tile-based AI denoise using the darktable.ai Lua API",
author = "Andrii Ryzhkov",
help = "https://docs.darktable.org/lua/stable/lua.scripts.manual/scripts/examples/ai_denoise"
}
script_data.destroy = destroy
return script_data