Probably stupid misuse of libpng api on my side ... I tried to add support for writing 16 bit per component PNGs into Cin. int FilePNG::write_frame(VFrame *frame, VFrame *data, FrameWriterUnit *unit) { PNGUnit *png_unit = (PNGUnit*)unit; png_structp png_ptr = 0; png_infop info_ptr = 0; VFrame *output_frame; int result = 1; int is_float = (frame->get_color_model() == BC_RGBA_FLOAT || frame->get_color_model() == BC_RGB_FLOAT); ==== here I try to get idea if project's colormodel actually *-FLOAT or not ==== data->set_compressed_size(0); //printf("FilePNG::write_frame 1\n"); native_cmodel = asset->png_use_alpha ? BC_RGBA8888 : BC_RGB888; if (is_float) native_cmodel = asset->png_use_alpha ? BC_RGBA16161616 : BC_RGB161616; === here I try to set native_colormodel to wide-channel integer format, if input was FP ==== if(frame->get_color_model() != native_cmodel) { if(!png_unit->temp_frame) png_unit->temp_frame = new VFrame(asset->width, asset->height, native_cmodel, 0); png_unit->temp_frame->transfer_from(frame); output_frame = png_unit->temp_frame; } else output_frame = frame; //printf("FilePNG::write_frame 1\n"); png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0); if( png_ptr ) { if( !setjmp(png_jmpbuf(png_ptr)) ) { info_ptr = png_create_info_struct(png_ptr); png_set_write_fn(png_ptr, data, (png_rw_ptr)write_function, (png_flush_ptr)flush_function); png_set_compression_level(png_ptr, asset->png_compression); png_set_IHDR(png_ptr, info_ptr, asset->width, asset->height, is_float ? 16 : 8, asset->png_use_alpha ? PNG_COLOR_TYPE_RGB_ALPHA : PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT); ==== here I try to call libpng with different bit depth depending on is_float ====== png_write_info(png_ptr, info_ptr); png_write_image(png_ptr, output_frame->get_rows()); png_write_end(png_ptr, info_ptr); result = 0; } png_destroy_write_struct(&png_ptr, &info_ptr); } if( result ) { char error[256]; png_error(png_ptr, error); fprintf(stderr, "FilePNG::write_frame failed: %s\n", error); } //printf("FilePNG::write_frame 3 %d\n", data->get_compressed_size()); return result; } I also modified int FilePNG::get_best_colormodel(Asset *asset, int driver) { if(asset->png_use_alpha) //return BC_RGBA8888; return BC_RGBA16161616; else //return BC_RGB888; return BC_RGB161616; } but probably those changes alone not enough, I get wrong colors or completely transparent picture in resulted png ?