Loading an image with generic_image, then writing wi... | pytroll/satpy

Describe the bug

When I load an image with the generic_image reader and immediately write it out again, the image changes. This happens because the generic_image reader returns float data, and then a default enhancement gets applied. However, not enhancing the data at all is even worse.

To Reproduce

from satpy import Scene
from glob import glob
seviri_files = glob("/media/nas/x21308/scratch/SEVIRI/202103300900/H-000*")
sc = Scene(filenames={"seviri_l1b_hrit": seviri_files})
sc.load(["natural_color"])
sc.save_datasets(writer="geotiff", filename="/tmp/natural-color-1.tif")

sc2 = Scene(filenames={"generic_image": ["/tmp/natural-color-1.tif"]})
sc2.load(["image"])
sc2.save_datasets(writer="geotiff", filename="/tmp/natural-color-2.tif")

Expected behavior

I expect both images to look the same.

Actual results

There is a difference, because the second image is getting re-enhanced:

[DEBUG: 2025-09-18 11:22:19 : satpy.readers.core.yaml_reader] Reading ('/home/gholl/checkouts/satpy/satpy/etc/readers/seviri_l1b_hrit.yaml',)
[DEBUG: 2025-09-18 11:22:19 : satpy.readers.core.yaml_reader] Assigning to seviri_l1b_hrit: ['/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000017___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000018___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000010___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000011___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000016___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000019___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000009___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000020___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000014___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000012___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000013___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000022___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000023___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000015___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000024___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000021___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-HRV______-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_016___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_039___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_039___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_039___-000007___-202103300900-__', 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'/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_087___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_087___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_087___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_087___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_097___-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_108___-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_120___-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-IR_134___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS006___-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000001___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000003___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000007___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000008___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000006___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000004___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-VIS008___-000002___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-WV_062___-000005___-202103300900-__', '/media/nas/x21308/scratch/SEVIRI/202103300900/H-000-MSG4__-MSG4________-WV_062___-000006___-202103300900-__', 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[INFO: 2025-09-18 11:22:19 : hrit_msg] No IMPF configuration field found in prologue.
[DEBUG: 2025-09-18 11:22:19 : satpy.composites.config_loader] Looking for composites config file seviri.yaml
[DEBUG: 2025-09-18 11:22:19 : pyorbital.tlefile] Path to the Pyorbital configuration (where e.g. platforms.txt is found): /home/gholl/miniforge3/envs/py313/lib/python3.13/site-packages/pyorbital/etc
[DEBUG: 2025-09-18 11:22:19 : satpy.composites.config_loader] Looking for composites config file visir.yaml
[DEBUG: 2025-09-18 11:22:19 : satpy.readers.core.yaml_reader] Requested orientation for Dataset None is 'native' (default). No flipping is applied.
[DEBUG: 2025-09-18 11:22:19 : satpy.readers.core.yaml_reader] Requested orientation for Dataset None is 'native' (default). No flipping is applied.
[DEBUG: 2025-09-18 11:22:19 : satpy.readers.core.yaml_reader] Requested orientation for Dataset None is 'native' (default). No flipping is applied.
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Applying sun zen correction
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Computing sun zenith angles.
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Apply the standard sun-zenith correction [1/cos(sunz)]
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Applying sun zen correction
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Computing sun zenith angles.
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Apply the standard sun-zenith correction [1/cos(sunz)]
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Applying sun zen correction
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Computing sun zenith angles.
[DEBUG: 2025-09-18 11:22:19 : satpy.modifiers.geometry] Apply the standard sun-zenith correction [1/cos(sunz)]
[DEBUG: 2025-09-18 11:22:19 : satpy.scene] Unloading dataset: DataID(name='IR_016', wavelength=WavelengthRange(min=1.5, central=1.64, max=1.78, unit='µm'), resolution=3000.403165817, calibration=<1>, modifiers=())
[DEBUG: 2025-09-18 11:22:19 : satpy.scene] Unloading dataset: DataID(name='VIS008', wavelength=WavelengthRange(min=0.74, central=0.81, max=0.88, unit='µm'), resolution=3000.403165817, calibration=<1>, modifiers=())
[DEBUG: 2025-09-18 11:22:19 : satpy.scene] Unloading dataset: DataID(name='VIS006', wavelength=WavelengthRange(min=0.56, central=0.635, max=0.71, unit='µm'), resolution=3000.403165817, calibration=<1>, modifiers=())
[DEBUG: 2025-09-18 11:22:19 : satpy.scene] Unloading dataset: DataID(name='IR_016', wavelength=WavelengthRange(min=1.5, central=1.64, max=1.78, unit='µm'), resolution=3000.403165817, calibration=<1>, modifiers=('sunz_corrected',))
[DEBUG: 2025-09-18 11:22:19 : satpy.scene] Unloading dataset: DataID(name='VIS008', wavelength=WavelengthRange(min=0.74, central=0.81, max=0.88, unit='µm'), resolution=3000.403165817, calibration=<1>, modifiers=('sunz_corrected',))
[DEBUG: 2025-09-18 11:22:19 : satpy.scene] Unloading dataset: DataID(name='VIS006', wavelength=WavelengthRange(min=0.56, central=0.635, max=0.71, unit='µm'), resolution=3000.403165817, calibration=<1>, modifiers=('sunz_corrected',))
[DEBUG: 2025-09-18 11:22:19 : satpy.writers.core.config] Reading ['/home/gholl/checkouts/satpy/satpy/etc/writers/geotiff.yaml']
[DEBUG: 2025-09-18 11:22:19 : rasterio.session] Could not import boto3, continuing with reduced functionality.
[DEBUG: 2025-09-18 11:22:20 : satpy.enhancements.enhancer] Adding enhancement configuration from file: /home/gholl/checkouts/satpy/satpy/etc/enhancements/generic.yaml
[DEBUG: 2025-09-18 11:22:20 : satpy.enhancements.enhancer] Adding enhancement configuration from file: /home/gholl/checkouts/pytroll-dwd-config/dev/enhancements/generic.yaml
[DEBUG: 2025-09-18 11:22:20 : satpy.enhancements.enhancer] Adding enhancement configuration from file: /home/gholl/checkouts/pytroll-dwd-config/oper/enhancements/generic.yaml
[DEBUG: 2025-09-18 11:22:20 : satpy.enhancements.enhancer] Adding enhancement configuration from file: /home/gholl/checkouts/satpy/satpy/etc/enhancements/seviri.yaml
[DEBUG: 2025-09-18 11:22:20 : satpy.enhancements.enhancer] Data for DataID(name='natural_color', resolution=3000.403165817) will be enhanced with options:
	[{'name': 'stretch', 'method': <function stretch at 0x7fde9f5716c0>, 'kwargs': {'stretch': 'crude', 'min_stretch': 0, 'max_stretch': 120}}, {'name': 'gamma', 'method': <function gamma at 0x7fde9f571760>, 'kwargs': {'gamma': 1.8}}]
[DEBUG: 2025-09-18 11:22:20 : trollimage.xrimage] Applying stretch crude with parameters {'min_stretch': 0, 'max_stretch': 120}
[DEBUG: 2025-09-18 11:22:20 : trollimage.xrimage] Applying gamma 1.8
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] Entering env context: <rasterio.env.Env object at 0x7fde9f1541a0>
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] Starting outermost env
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] No GDAL environment exists
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] New GDAL environment <rasterio._env.GDALEnv object at 0x7fdea26925f0> created
[DEBUG: 2025-09-18 11:22:20 : rasterio._filepath] Installing FilePath filesystem handler plugin...
[DEBUG: 2025-09-18 11:22:20 : rasterio._env] GDAL_DATA found in environment.
[DEBUG: 2025-09-18 11:22:20 : rasterio._env] PROJ_DATA found in environment.
[DEBUG: 2025-09-18 11:22:20 : rasterio._env] Started GDALEnv: self=<rasterio._env.GDALEnv object at 0x7fdea26925f0>.
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] Entered env context: <rasterio.env.Env object at 0x7fde9f1541a0>
[DEBUG: 2025-09-18 11:22:20 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:20 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:20 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:20 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] Exiting env context: <rasterio.env.Env object at 0x7fde9f1541a0>
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] Cleared existing <rasterio._env.GDALEnv object at 0x7fdea26925f0> options
[DEBUG: 2025-09-18 11:22:20 : rasterio._env] Stopped GDALEnv <rasterio._env.GDALEnv object at 0x7fdea26925f0>.
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] Exiting outermost env
[DEBUG: 2025-09-18 11:22:20 : rasterio.env] Exited env context: <rasterio.env.Env object at 0x7fde9f1541a0>
[INFO: 2025-09-18 11:22:20 : satpy.writers.core.base] Computing and writing results...
[DEBUG: 2025-09-18 11:22:22 : satpy.readers.core.yaml_reader] Reading ('/home/gholl/checkouts/satpy/satpy/etc/readers/generic_image.yaml',)
[DEBUG: 2025-09-18 11:22:22 : satpy.readers.core.yaml_reader] Assigning to generic_image: ['/tmp/natural-color-1.tif']
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Entering env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Starting outermost env
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] No GDAL environment exists
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] New GDAL environment <rasterio._env.GDALEnv object at 0x7fde9f2800d0> created
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] GDAL_DATA found in environment.
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] PROJ_DATA found in environment.
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] Started GDALEnv: self=<rasterio._env.GDALEnv object at 0x7fde9f2800d0>.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Entered env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Sharing flag: 0
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Dataset <open DatasetReader name='/tmp/natural-color-1.tif' mode='r'> is started.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exiting env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Cleared existing <rasterio._env.GDALEnv object at 0x7fde9f2800d0> options
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] Stopped GDALEnv <rasterio._env.GDALEnv object at 0x7fde9f2800d0>.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exiting outermost env
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exited env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Entering env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Starting outermost env
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] No GDAL environment exists
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] New GDAL environment <rasterio._env.GDALEnv object at 0x7fdea263b700> created
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] GDAL_DATA found in environment.
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] PROJ_DATA found in environment.
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] Started GDALEnv: self=<rasterio._env.GDALEnv object at 0x7fdea263b700>.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Entered env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Sharing flag: 0
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Dataset <open DatasetReader name='/tmp/natural-color-1.tif' mode='r'> is started.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exiting env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Cleared existing <rasterio._env.GDALEnv object at 0x7fdea263b700> options
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] Stopped GDALEnv <rasterio._env.GDALEnv object at 0x7fdea263b700>.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exiting outermost env
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exited env context: <rasterio.env.Env object at 0x7fde9f248a50>
[DEBUG: 2025-09-18 11:22:22 : satpy.composites.config_loader] Looking for composites config file images.yaml
[DEBUG: 2025-09-18 11:22:22 : satpy.composites.config_loader] No composite config found called images.yaml
[DEBUG: 2025-09-18 11:22:22 : satpy.readers.generic_image] Reading 'image.'
[DEBUG: 2025-09-18 11:22:22 : satpy.writers.core.config] Reading ['/home/gholl/checkouts/satpy/satpy/etc/writers/geotiff.yaml']
[DEBUG: 2025-09-18 11:22:22 : satpy.enhancements.enhancer] Adding enhancement configuration from file: /home/gholl/checkouts/satpy/satpy/etc/enhancements/generic.yaml
[DEBUG: 2025-09-18 11:22:22 : satpy.enhancements.enhancer] Adding enhancement configuration from file: /home/gholl/checkouts/pytroll-dwd-config/dev/enhancements/generic.yaml
[DEBUG: 2025-09-18 11:22:22 : satpy.enhancements.enhancer] Adding enhancement configuration from file: /home/gholl/checkouts/pytroll-dwd-config/oper/enhancements/generic.yaml
[DEBUG: 2025-09-18 11:22:22 : satpy.enhancements.enhancer] Data for DataID(name='image', modifiers=()) will be enhanced with options:
	[{'name': 'stretch', 'method': <function stretch at 0x7fde9f5716c0>, 'kwargs': {'stretch': 'linear'}}]
[DEBUG: 2025-09-18 11:22:22 : trollimage.xrimage] Applying stretch linear with parameters {}
[DEBUG: 2025-09-18 11:22:22 : trollimage.xrimage] Perform a linear contrast stretch.
[DEBUG: 2025-09-18 11:22:22 : trollimage.xrimage] Calculate the histogram quantiles: 
[DEBUG: 2025-09-18 11:22:22 : trollimage.xrimage] Left and right quantiles: 0.005 0.005
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Entering env context: <rasterio.env.Env object at 0x7fde9f4f36f0>
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Starting outermost env
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] No GDAL environment exists
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] New GDAL environment <rasterio._env.GDALEnv object at 0x7fde9f57e1a0> created
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] GDAL_DATA found in environment.
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] PROJ_DATA found in environment.
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] Started GDALEnv: self=<rasterio._env.GDALEnv object at 0x7fde9f57e1a0>.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Entered env context: <rasterio.env.Env object at 0x7fde9f4f36f0>
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio._base] Nodata success: 0, Nodata value: 0.000000
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exiting env context: <rasterio.env.Env object at 0x7fde9f4f36f0>
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Cleared existing <rasterio._env.GDALEnv object at 0x7fde9f57e1a0> options
[DEBUG: 2025-09-18 11:22:22 : rasterio._env] Stopped GDALEnv <rasterio._env.GDALEnv object at 0x7fde9f57e1a0>.
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exiting outermost env
[DEBUG: 2025-09-18 11:22:22 : rasterio.env] Exited env context: <rasterio.env.Env object at 0x7fde9f4f36f0>
[INFO: 2025-09-18 11:22:22 : satpy.writers.core.base] Computing and writing results...
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata value read from file: None
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata values: [None]
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] all_valid: False
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] mask_flags: ([<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.all_valid: 1>])
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Jump straight to _read()
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Window: Window(col_off=0, row_off=0, width=3712, height=3712)
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] IO window xoff=0.0 yoff=0.0 width=3712.0 height=3712.0
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata value read from file: None
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata values: [None]
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] all_valid: False
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] mask_flags: ([<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.all_valid: 1>])
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Jump straight to _read()
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Window: Window(col_off=0, row_off=0, width=3712, height=3712)
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] IO window xoff=0.0 yoff=0.0 width=3712.0 height=3712.0
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata value read from file: None
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata values: [None]
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] all_valid: False
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] mask_flags: ([<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.all_valid: 1>])
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Jump straight to _read()
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Window: Window(col_off=0, row_off=0, width=3712, height=3712)
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] IO window xoff=0.0 yoff=0.0 width=3712.0 height=3712.0
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata value read from file: None
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Output nodata values: [None]
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] all_valid: False
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] mask_flags: ([<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.per_dataset: 2>, <MaskFlags.alpha: 4>], [<MaskFlags.all_valid: 1>])
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Jump straight to _read()
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] Window: Window(col_off=0, row_off=0, width=3712, height=3712)
[DEBUG: 2025-09-18 11:22:22 : rasterio._io] IO window xoff=0.0 yoff=0.0 width=3712.0 height=3712.0

Screenshots

Environment Info:

OS: openSUSE Leap 15.6
Satpy Version: main

Additional context

I tried to create a custom reader with a standard name, then set this to image_ready, but this just makes the situation worse:

reader:
    name: special-image
    description: reads RGBs from geotiff files
    reader: !!python/name:satpy.readers.core.yaml_reader.FileYAMLReader
    sensors: [world-images]

file_types:
    special-image:
      file_reader: !!python/name:satpy.readers.generic_image.GenericImageFileHandler
      file_patterns:
        - "{name}.tif"

datasets:
  special-image:
    file_type: special-image
    name: special-image
    standard_name: image_ready

What happens here is that trollimage is getting data with floats between 0 and 255, but expects floats between 0 and 1.

As a workaround, this enhancement works (with standard_name: rgb_image):

  rgb_image:
    standard_name: rgb_image
    operations:
      - name: stretch
        method: !!python/name:satpy.enhancements.contrast.stretch
        kwargs:
          stretch: crude
          min_stretch: [0, 0, 0]
          max_stretch: [255, 255, 255]

As a solution, if the GenericImageFileHandler would return integer data, I think satpy wouldn't enhance the data and the round trip load/save should work.

Why am I doing this? I'm creating an RGB world composite by writing each component image to a joint world area, then loading those with a dedicated reader and combining them with the LongitudeMaskingCompositor.

Loading an image with generic_image, then writing with geotiff, changes the image

Description

Contributor guide

First steps

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