Question: I need to convert a DNG file to PNG using python. I found a post here how to convert DNG: Opencv Python open dng format The code I tried: #open dng and convert import rawpy import imageio import os os.chdir(r'C:\Path\to\dir') path = r'path\to\file' with rawpy.imread(path) as raw: rgb = raw.postprocess() rgb_img.save('image.png')  However, it spits out the following errors: line 13, in <module> rgb = raw.postprocess() File "rawpy\_rawpy.pyx", line 887, in rawpy._rawpy.RawPy.postprocess File "rawpy\_rawpy.pyx", line 790, in rawpy._rawpy.RawPy.dcraw_process File "rawpy\_rawpy.pyx", line 438, in rawpy._rawpy.RawPy.ensure_unpack File "rawpy\_rawpy.pyx", line 432, in rawpy._rawpy.RawPy.unpack File "rawpy\_rawpy.pyx", line 936, in rawpy._rawpy.RawPy.handle_error rawpy._rawpy.LibRawTooBigError: b'Image too big for processing'  Is there either an alternative to convert the DNG files, or a way to bypass this error? Info from exiftool: ExifTool Version Number : 11.88 File Name : DSCF0001.DNG Directory : . File Size : 1313 MB File Modification Date/Time : 2022:08:24 12:06:31+01:00 File Access Date/Time : 2022:08:25 08:17:15+01:00 File Inode Change Date/Time : 2022:08:24 15:19:04+01:00 File Permissions : rwxrwxrwx File Type : DNG File Type Extension : dng MIME Type : image/x-adobe-dng Exif Byte Order : Little-endian (Intel, II) Make : FUJIFILM Camera Model Name : GFX 100 Preview Image Start : 115208860 Orientation : Horizontal (normal) Rows Per Strip : 3000 Preview Image Length : 3011337 Software : FUJIFILM Pixel Shift Combiner 1.2.0.2 (Real Color + High Resolution mode) Modify Date : 2022:08:24 12:06:29 Artist : Subfile Type : Full-resolution image Image Width : 23296 Image Height : 17472 Bits Per Sample : 16 16 16 Compression : JPEG Photometric Interpretation : Linear Raw Samples Per Pixel : 3 Planar Configuration : Chunky Tile Width : 128 Tile Length : 96 Tile Offsets : (Binary data 341026 bytes, use -b option to extract) Tile Byte Counts : (Binary data 198743 bytes, use -b option to extract) Black Level : 256 255 256 White Level : 65535 65535 65535 Default Scale : 1 1 Default Crop Origin : 16 12 Default Crop Size : 23264 17448 Anti Alias Strength : 1 Best Quality Scale : 1 Opcode List 3 : WarpRectilinear, FixVignetteRadial Rating : 0 Copyright : Exposure Time : 1/125 F Number : 8.0 Exposure Program : Manual ISO : 100 Sensitivity Type : Standard Output Sensitivity Standard Output Sensitivity : 100 Exif Version : 0230 Date/Time Original : 2019:03:10 00:44:16 Create Date : 2019:03:10 00:44:16 Shutter Speed Value : 1/125 Aperture Value : 8.0 Brightness Value : 8.57 Exposure Compensation : 0 Max Aperture Value : 2.0 Metering Mode : Multi-segment Light Source : Unknown Flash : No Flash Focal Length : 110.0 mm Version : 0130 Internal Serial Number : Quality : NORMAL White Balance : Auto Saturation : 0 (normal) White Balance Fine Tune : Red +0, Blue +0 Noise Reduction : 0 (normal) Fuji Flash Mode : Manual Flash Exposure Comp : 0 Focus Mode : Manual AF Mode : No Focus Pixel : 2001 1501 AF-S Priority : Release AF-C Priority : Release Focus Mode 2 : AF-M AF Area Mode : Single Point AF Area Point Size : n/a AF Area Zone Size : n/a AF-C Setting : Set 1 (multi-purpose) AF-C Tracking Sensitivity : 2 AF-C Speed Tracking Sensitivity : 0 AF-C Zone Area Switching : Auto Slow Sync : Off Picture Mode : Manual Exposure Count : 1 Shadow Tone : 0 (normal) Highlight Tone : 0 (normal) Lens Modulation Optimizer : On Grain Effect : Off Color Chrome Effect : Off Crop Mode : n/a Color Chrome FX Blue : Off Shutter Type : Electronic Auto Bracketing : Unknown (6) Sequence Number : 1 Drive Mode : Single Drive Speed : n/a Blur Warning : None Focus Warning : Good Exposure Warning : Good Dynamic Range : Standard Film Mode : F0/Standard (Provia) Dynamic Range Setting : Manual Development Dynamic Range : 100 Min Focal Length : 110 Max Focal Length : 110 Max Aperture At Min Focal : 2 Max Aperture At Max Focal : 2 Image Stabilization : Sensor-shift; Off; 0 Image Generation : Original Image Image Count : 34 Flicker Reduction : Off (0x0002) Faces Detected : 0 Num Face Elements : 0 Color Space : Uncalibrated Focal Plane X Resolution : 5320 Focal Plane Y Resolution : 5320 Focal Plane Resolution Unit : cm File Source : Digital Camera Scene Type : Directly photographed Custom Rendered : Normal Exposure Mode : Auto Focal Length In 35mm Format : 87 mm Scene Capture Type : Standard Sharpness : Unknown (3) Subject Distance Range : Unknown (48) Serial Number : Lens Info : 110mm f/2 Lens Make : FUJIFILM Lens Model : GF110mmF2 R LM WR Lens Serial Number : DNG Version : 1.4.0.0 DNG Backward Version : 1.1.0.0 Unique Camera Model : FUJIFILM GFX 100 Color Matrix 1 : 1.7191 -1.1 0.1278 -0.3574 1.1733 0.2076 -0.0002 0.0497 0.654 Color Matrix 2 : 1.6212 -0.8423 -0.1583 -0.4336 1.2583 0.1937 -0.0195 0.0726 0.6199 Analog Balance : 1 1 1 As Shot Neutral : 0.5644 1 0.5153 Baseline Exposure : -0.01 Baseline Noise : 1 Baseline Sharpness : 1.33 Linear Response Limit : 1 Camera Serial Number : DNG Lens Info : 110mm f/2 Shadow Scale : 1 DNG Private Data : (Binary data 114927728 bytes, use -b option to extract) Calibration Illuminant 1 : Standard Light A Calibration Illuminant 2 : D65 Aperture : 8.0 Image Size : 23296x17472 Megapixels : 407.0 Preview Image : (Binary data 3011337 bytes, use -b option to extract) Scale Factor To 35 mm Equivalent: 0.8 Shutter Speed : 1/125 Circle Of Confusion : 0.038 mm Field Of View : 23.4 deg Focal Length : 110.0 mm (35 mm equivalent: 87.0 mm) Hyperfocal Distance : 39.81 m Light Value : 13.0 

Answer: There seems to be a limit of 2GB for the fully expanded in memory image. I don't mean the space your DNG requires on disk, I mean the following number: ImageHeight * ImageWidth * NumberOfChannels * BytesPerSample  So it would be useful if you used exiftool to tell us those parameters, by clicking edit under your question and adding the output from: exiftool YOURIMAGE.DNG  The limit is enforced in the variable imgdata.params.max_raw_memory_mb which is set to 2048 in the underlying libraw C code. I am not immediately sure how you could set that through the Python interface.  You may have some success converting it to a PNG or a TIFF with ImageMagick as follows: magick YOURIMAGE.DNG converted.png  If that works, you could use wand which is a Python binding to Imagemagick.  You could try with ufraw maybe, along the lines of: ufraw-batch --out-type=png --out-depth=16 --output=result.png YOURIMAGE.dng