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plazas merged 3 commits into from
Nov 4, 2026
Merged

DM-56927: Update DP2 color image NB tutorial #243

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fd1490e
Update tutorial on color images
plazas Nov 3, 2026
26fac52
Update 103_9_Custom_color_images.ipynb
plazas Nov 3, 2026
4c6915f
Update notebook
plazas Nov 4, 2026
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46 changes: 37 additions & 9 deletions DP2/100_How_to_use_RSP_tools/103_Image_access_and_display/103_9_Custom_color_images.ipynb
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Expand Up @@ -22,7 +22,7 @@
"Data Release: [Data Preview 2](https://dp2.lsst.io/)\\\n",
"Container Size: Large\\\n",
"LSST Science Pipelines version: r30.0.11\\\n",
"Last verified to run: 2026-09-21\\\n",
"Last verified to run: 2026-11-04\\\n",
"Repository: [github.com/lsst/tutorial-notebooks](https://github.com/lsst/tutorial-notebooks)\\\n",
"DOI: [10.11578/rubin/dc.20250909.20](https://doi.org/10.11578/rubin/dc.20250909.20)"
]
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"id": "cell-008",
"metadata": {},
"source": [
"Create an instance of the butler, and assert that it exists."
"Create an instance of the butler."
]
},
{
Expand Down Expand Up @@ -219,12 +219,40 @@
"pretty_pic_config = PrettyPictureTask.ConfigClass()"
]
},
{
"cell_type": "markdown",
"id": "cell-014a",
"metadata": {},
"source": [
"### 2.1. `localContrastConfig.doLocalContrast`\n",
"\n",
"This parameter toggles local-contrast enhancement in the luminance channel. It defaults to `True`; turn it off for small images or faster processing, and keep it on to boost mid-scale detail in extended objects (e.g., subtle spiral arms). When enabled, contrast is enhanced before color mapping, revealing structures that are close in brightness to their surroundings."
]
},
{
"cell_type": "markdown",
"id": "cell-014b",
"metadata": {},
"source": [
">**Warning**: For DP2, this parameter must be set to `False` to avoid a known bug related to image size mismatches."
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "cell-014c",
"metadata": {},
"outputs": [],
"source": [
"pretty_pic_config.doLocalContrast = False"
]
},
{
"cell_type": "markdown",
"id": "cell-017",
"metadata": {},
"source": [
"### 2.1. `imageRemappingConfig.absMax`\n",
"### 2.2. `imageRemappingConfig.absMax`\n",
"\n",
"This parameter sets the input data value (for Rubin data, in nJy) that will be treated as \"white\" in the output image.\n",
"In this context, \"white\" means the maximum display intensity in the output RGB image.\n",
Expand All @@ -249,7 +277,7 @@
"id": "cell-019",
"metadata": {},
"source": [
"### 2.2. `luminanceConfig.stretch`\n",
"### 2.3. `luminanceConfig.stretch`\n",
"\n",
"This parameter controls the strength of the arcsinh stretch applied to the luminance channel, as defined in [Lupton et al. 2004](https://ui.adsabs.harvard.edu/abs/2004PASP..116..133L/abstract).\n",
"The arcsinh function compresses the dynamic range of the image while still preserving faint structures, making it well-suited for astronomical images where bright sources and faint details coexist. Smaller values of stretch produce a more aggressive compression that enhances faint features but can cause bright regions to saturate, while larger values approach a nearly linear scaling."
Expand All @@ -270,7 +298,7 @@
"id": "cell-021",
"metadata": {},
"source": [
"### 2.3. `luminanceConfig.highlight`, `luminanceConfig.shadow`, `luminanceConfig.midtone`\n",
"### 2.4. `luminanceConfig.highlight`, `luminanceConfig.shadow`, `luminanceConfig.midtone`\n",
"\n",
"These parameters control a tone-mapping function applied after the arcsinh stretch, similar to the highlight, shadow, and midtone sliders in many photo-editing applications.\n",
"They determine how the luminance values, now scaled to the 0–1 range, are mapped to the final display brightness.\n",
Expand All @@ -297,7 +325,7 @@
"id": "cell-023",
"metadata": {},
"source": [
"### 2.4. `doPsfDeconvolve`\n",
"### 2.5. `doPsfDeconvolve`\n",
"\n",
"This parameter controls whether the image will undergo Point Spread Function (PSF) deconvolution as part of the processing. Setting it to `False` disables PSF deconvolution, which can simplify and speed up the processing, especially for tutorial or exploratory work. When enabled, PSF deconvolution can sharpen features in the image by compensating for the blurring effects of the point-spread function, but it also increases computational complexity and may amplify noise in low signal-to-noise regions."
]
Expand All @@ -317,7 +345,7 @@
"id": "cell-025",
"metadata": {},
"source": [
"### 2.5. `exposureBracketerConfig.exposureBrackets`\n",
"### 2.6. `exposureBracketerConfig.exposureBrackets`\n",
"\n",
"This parameter enables the use of exposure bracketing, an advanced technique for further compressing the dynamic range of an image. Exposure brackets combine differently scaled versions of the same image to retain detail in both the brightest and faintest regions, similar to high dynamic range (HDR) processing in photography. While powerful, this feature can require careful tuning to achieve the desired visual effect. For simplicity and consistency in this tutorial, it is set to `None`, which disables bracketing and uses a single stretch for the entire image."
]
Expand All @@ -337,7 +365,7 @@
"id": "cell-027",
"metadata": {},
"source": [
"### 2.6. `colorConfig.maxChroma` and `colorConfig.saturation`\n",
"### 2.7. `colorConfig.maxChroma` and `colorConfig.saturation`\n",
"\n",
"These parameters control how color intensity changes with brightness.\n",
"Increasing `maxChroma` (> 0) and `saturation` produces richer, more vibrant colors compared to the default settings, enhancing visual appeal while preserving the relative color balance of objects in the image.\n",
Expand All @@ -360,7 +388,7 @@
"id": "cell-029",
"metadata": {},
"source": [
"### 2.7. `channelConfig`\n",
"### 2.8. `channelConfig`\n",
"\n",
"This setting controls how each input band contributes to the red, green, and blue channels of the final RGB image. In the default configuration, the *g* band maps entirely to blue, the *r* band to green, and the *i* band to red, producing a straightforward g–r–i color composite (with the `rgb` values in the [0,1] range).\n",
"\n",
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