pic_scale/colors/
lab_scaler.rs

1/*
2 * Copyright (c) Radzivon Bartoshyk 3/2026. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without modification,
5 * are permitted provided that the following conditions are met:
6 *
7 * 1.  Redistributions of source code must retain the above copyright notice, this
8 * list of conditions and the following disclaimer.
9 *
10 * 2.  Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation
12 * and/or other materials provided with the distribution.
13 *
14 * 3.  Neither the name of the copyright holder nor the names of its
15 * contributors may be used to endorse or promote products derived from
16 * this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
24 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
25 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29use crate::colors::common_splitter::{SplitPlanInterceptor, Splitter};
30use crate::plan::Resampling;
31use crate::validation::PicScaleError;
32use crate::{ImageSize, ImageStore, ImageStoreMut, ResamplingFunction, Scaler, ThreadingPolicy};
33use colorutils_rs::{
34    SRGB_TO_XYZ_D65, TransferFunction, XYZ_TO_SRGB_D65, lab_to_srgb, lab_with_alpha_to_rgba,
35    rgb_to_lab, rgba_to_lab_with_alpha,
36};
37use std::sync::Arc;
38
39#[derive(Debug, Copy, Clone)]
40/// Converts image to *CIE LAB* components scales it and convert back
41pub struct LabScaler {
42    pub(crate) scaler: Scaler,
43}
44
45struct LabRgbSplitter {}
46
47impl Splitter<u8, f32, 3> for LabRgbSplitter {
48    fn split(&self, from: &ImageStore<'_, u8, 3>, into: &mut ImageStoreMut<'_, f32, 3>) {
49        let lab_stride = into.width as u32 * 3u32 * size_of::<f32>() as u32;
50
51        rgb_to_lab(
52            from.buffer.as_ref(),
53            from.width as u32 * 3u32,
54            into.buffer.borrow_mut(),
55            lab_stride,
56            into.width as u32,
57            into.height as u32,
58            &SRGB_TO_XYZ_D65,
59            TransferFunction::Srgb,
60        );
61    }
62
63    fn merge(&self, from: &ImageStore<'_, f32, 3>, into: &mut ImageStoreMut<'_, u8, 3>) {
64        let new_lab_stride = into.width as u32 * 3 * size_of::<f32>() as u32;
65        lab_to_srgb(
66            from.buffer.as_ref(),
67            new_lab_stride,
68            into.buffer.borrow_mut(),
69            into.width as u32 * 3,
70            into.width as u32,
71            into.height as u32,
72        );
73    }
74    fn bit_depth(&self) -> usize {
75        8
76    }
77}
78
79struct LabRgbaSplitter {}
80
81impl Splitter<u8, f32, 4> for LabRgbaSplitter {
82    fn split(&self, from: &ImageStore<'_, u8, 4>, into: &mut ImageStoreMut<'_, f32, 4>) {
83        let lab_stride = into.width as u32 * 4u32 * size_of::<f32>() as u32;
84
85        rgba_to_lab_with_alpha(
86            from.buffer.as_ref(),
87            from.width as u32 * 4u32,
88            into.buffer.borrow_mut(),
89            lab_stride,
90            into.width as u32,
91            into.height as u32,
92            &SRGB_TO_XYZ_D65,
93            TransferFunction::Srgb,
94        );
95    }
96
97    fn merge(&self, from: &ImageStore<'_, f32, 4>, into: &mut ImageStoreMut<'_, u8, 4>) {
98        let new_lab_stride = into.width as u32 * 4 * size_of::<f32>() as u32;
99        lab_with_alpha_to_rgba(
100            from.buffer.as_ref(),
101            new_lab_stride,
102            into.buffer.borrow_mut(),
103            into.width as u32 * 4,
104            into.width as u32,
105            into.height as u32,
106            &XYZ_TO_SRGB_D65,
107            TransferFunction::Srgb,
108        );
109    }
110
111    fn bit_depth(&self) -> usize {
112        8
113    }
114}
115
116impl LabScaler {
117    pub fn new(filter: ResamplingFunction) -> Self {
118        LabScaler {
119            scaler: Scaler::new(filter),
120        }
121    }
122}
123
124impl LabScaler {
125    pub fn set_threading_policy(&mut self, threading_policy: ThreadingPolicy) {
126        self.scaler.threading_policy = threading_policy;
127    }
128
129    pub fn plan_rgb_resampling(
130        &self,
131        source_size: ImageSize,
132        target_size: ImageSize,
133    ) -> Result<Arc<Resampling<u8, 3>>, PicScaleError> {
134        let intercept = self
135            .scaler
136            .plan_rgb_resampling_f32(source_size, target_size)?;
137        let scratch_size = intercept.scratch_size();
138        Ok(Arc::new(SplitPlanInterceptor {
139            intercept,
140            splitter: Arc::new(LabRgbSplitter {}),
141            inner_scratch: scratch_size,
142        }))
143    }
144
145    pub fn plan_rgba_resampling(
146        &self,
147        source_size: ImageSize,
148        target_size: ImageSize,
149        premultiply_alpha: bool,
150    ) -> Result<Arc<Resampling<u8, 4>>, PicScaleError> {
151        let intercept =
152            self.scaler
153                .plan_rgba_resampling_f32(source_size, target_size, premultiply_alpha)?;
154        let scratch_size = intercept.scratch_size();
155        Ok(Arc::new(SplitPlanInterceptor {
156            intercept,
157            splitter: Arc::new(LabRgbaSplitter {}),
158            inner_scratch: scratch_size,
159        }))
160    }
161}
pic_scale/colors/lab_scaler.rs

pic_scale/colors/
lab_scaler.rs
