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(
49        &self,
50        from: &ImageStore<'_, u8, 3>,
51        into: &mut ImageStoreMut<'_, f32, 3>,
52    ) -> Result<(), PicScaleError> {
53        let mut dst_buffer = into.to_colorutils_buffer_mut();
54
55        rgb_to_lab(
56            &from.to_colorutils_buffer(),
57            &mut dst_buffer,
58            &SRGB_TO_XYZ_D65,
59            TransferFunction::Srgb,
60        )
61        .map_err(|x| PicScaleError::Generic(x.to_string()))
62    }
63
64    fn merge(
65        &self,
66        from: &ImageStore<'_, f32, 3>,
67        into: &mut ImageStoreMut<'_, u8, 3>,
68    ) -> Result<(), PicScaleError> {
69        let mut dst_buffer = into.to_colorutils_buffer_mut();
70
71        lab_to_srgb(&from.to_colorutils_buffer(), &mut dst_buffer)
72            .map_err(|x| PicScaleError::Generic(x.to_string()))
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(
83        &self,
84        from: &ImageStore<'_, u8, 4>,
85        into: &mut ImageStoreMut<'_, f32, 4>,
86    ) -> Result<(), PicScaleError> {
87        let mut dst_buffer = into.to_colorutils_buffer_mut();
88        rgba_to_lab_with_alpha(
89            &from.to_colorutils_buffer(),
90            &mut dst_buffer,
91            &SRGB_TO_XYZ_D65,
92            TransferFunction::Srgb,
93        )
94        .map_err(|x| PicScaleError::Generic(x.to_string()))
95    }
96
97    fn merge(
98        &self,
99        from: &ImageStore<'_, f32, 4>,
100        into: &mut ImageStoreMut<'_, u8, 4>,
101    ) -> Result<(), PicScaleError> {
102        let mut dst_buffer = into.to_colorutils_buffer_mut();
103        lab_with_alpha_to_rgba(
104            &from.to_colorutils_buffer(),
105            &mut dst_buffer,
106            &XYZ_TO_SRGB_D65,
107            TransferFunction::Srgb,
108        )
109        .map_err(|x| PicScaleError::Generic(x.to_string()))
110    }
111
112    fn bit_depth(&self) -> usize {
113        8
114    }
115}
116
117impl LabScaler {
118    pub fn new(filter: ResamplingFunction) -> Self {
119        LabScaler {
120            scaler: Scaler::new(filter),
121        }
122    }
123}
124
125impl LabScaler {
126    pub fn set_threading_policy(&mut self, threading_policy: ThreadingPolicy) -> LabScaler {
127        self.scaler.threading_policy = threading_policy;
128        *self
129    }
130
131    pub fn plan_rgb_resampling(
132        &self,
133        source_size: ImageSize,
134        target_size: ImageSize,
135    ) -> Result<Arc<Resampling<u8, 3>>, PicScaleError> {
136        let intercept = self
137            .scaler
138            .plan_rgb_resampling_f32(source_size, target_size)?;
139        let scratch_size = intercept.scratch_size();
140        Ok(Arc::new(SplitPlanInterceptor {
141            intercept,
142            splitter: Arc::new(LabRgbSplitter {}),
143            inner_scratch: scratch_size,
144        }))
145    }
146
147    pub fn plan_rgba_resampling(
148        &self,
149        source_size: ImageSize,
150        target_size: ImageSize,
151        premultiply_alpha: bool,
152    ) -> Result<Arc<Resampling<u8, 4>>, PicScaleError> {
153        let intercept =
154            self.scaler
155                .plan_rgba_resampling_f32(source_size, target_size, premultiply_alpha)?;
156        let scratch_size = intercept.scratch_size();
157        Ok(Arc::new(SplitPlanInterceptor {
158            intercept,
159            splitter: Arc::new(LabRgbaSplitter {}),
160            inner_scratch: scratch_size,
161        }))
162    }
163}
pic_scale/colors/lab_scaler.rs

pic_scale/colors/
lab_scaler.rs
