save_pfm(): Instance is volumetric, only the first slice wil

Error message

save_pfm(): Instance is volumetric, only the first slice will be saved in file '%s'.

What it means

save_pfm() writes a 2D floating-point radiance map (Portable Float Map); CImg warns when _depth>1 because PFM has no volumetric extension and only the first z-slice (depth 0) is written. The remaining slices are silently dropped. Emitted via cimg::warn(), non-fatal.

Source

Thrown at ucrop/src/main/jni/CImg.h:62486

    const CImg<T>& save_pfm(const char *const filename) const {
      get_mirror('y')._save_pfm(0,filename);
      return *this;
    }

    //! Save image as a PFM file \overloading.
    const CImg<T>& save_pfm(std::FILE *const file) const {
      get_mirror('y')._save_pfm(file,0);
      return *this;
    }

    const CImg<T>& _save_pfm(std::FILE *const file, const char *const filename) const {
      if (!file && !filename)
        throw CImgArgumentException(_cimg_instance
                                    "save_pfm(): Specified filename is (null).",
                                    cimg_instance);
      if (is_empty()) { cimg::fempty(file,filename); return *this; }
      if (_depth>1)
        cimg::warn(_cimg_instance
                   "save_pfm(): Instance is volumetric, only the first slice will be saved in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");
      if (_spectrum>3)
        cimg::warn(_cimg_instance
                   "save_pfm(): image instance is multispectral, only the three first channels will be saved "
                   "in file '%s'.",
                   cimg_instance,
                   filename?filename:"(FILE*)");

      std::FILE *const nfile = file?file:cimg::fopen(filename,"wb");
      const T
        *ptr_r = data(0,0,0,0),
        *ptr_g = (_spectrum>=2)?data(0,0,0,1):0,
        *ptr_b = (_spectrum>=3)?data(0,0,0,2):0;
      const unsigned int buf_size = std::min(1024*1024U,_width*_height*(_spectrum==1?1:3));

      std::fprintf(nfile,"P%c\n%u %u\n1.0\n",

View on GitHub (pinned to f788b534b4)

Solutions

Save each slice separately: for (int z=0; z<img.depth(); ++z) img.get_slice(z).save_pfm(name_for_z)
Use a volumetric-capable format (multi-page TIFF via save_tiff, or DICOM/NIfTI if available)
If depth>1 is a bug, fix constructor argument order: CImg(w,h,1,c) for 2D images

Example fix

// before
volume.save_pfm("out.pfm");         // only slice 0 saved
// after
for (int z = 0; z < volume.depth(); ++z)
  volume.get_slice(z).save_pfm(cimg::format("out_%03d.pfm", z));

Defensive patterns

Strategy: validation

Validate before calling

if (img.depth() > 1)
  for (int z = 0; z < img.depth(); ++z) img.get_slice(z).save_pfm(cimg::format("out_%03d.pfm", z));
else
  img.save_pfm("out.pfm");

Type guard

bool is_2d(const cimg_library::CImg<T>& img) { return img.depth() == 1; }

Try / catch

try { img.save_pfm("out.pfm"); } catch (CImgException& e) { /* handle */ }

Prevention

Check depth() before 2D-only savers
Save volumes to TIFF or native CImg format
Verify constructor argument order (w,h,d,c) for 2D images

When it happens

Trigger: Calling save_pfm() on a volumetric CImg where _depth>1, e.g. after loading a multi-slice TIFF/NIfTI stack, building a 3D volume from slices, or an image accidentally constructed with depth>1.

Common situations: HDR pipelines handling image stacks; saving 3D medical imaging data to PFM; bugs where width/height/depth constructor arguments were passed in the wrong order producing unintended depth.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of Yalantis/uCrop@f788b534b4 (2026-09-08). Data as JSON: /api/errors/355a0ff49d85da2b. Report an issue: GitHub.