Tiff
One parsed TIFF Image File Directory — a single raster in the file. A pyramided GeoTIFF (a COG, or anything gdaladdo has touched) holds the full-resolution image in the first IFD and each successively coarser overview in its own IFD; GeoTiffDataset keeps them as a resolution ladder and picks one per rendered tile.
Strip-organized rasters are normalized to the tiled shape: a strip is just a block as wide as the image and blockHeight rows tall, so block indexing and decoding stay on one path.
Properties
Bits of the first sample — the elevation / gray band, and the width every band shares in the layouts we decode.
Uncompressed byte size of a full block — what the decompressors size their output to.
Block height in pixels — TileLength, or RowsPerStrip for strips.
Number of blocks across the raster.
Number of blocks down the raster.
Block width in pixels — TileWidth, or the image width for strips.
Bytes one pixel occupies in a decoded block (all samples, chunky layout).
ExtraSamples — a first entry of 1 (associated) or 2 (unassociated) marks an alpha band.
True when the raster carries a vertical CRS — the one place GeoTIFF states outright that its pixels are heights, since only a height field is georeferenced vertically. Absent from most DEMs all the same, so it confirms elevation rather than ruling it out.
True when this IFD is a reduced-resolution overview of the full-size image.
Per-sample SampleFormat (unsigned / signed / IEEE float), defaulted to unsigned.
NewSubfileType bit field: bit 0 = reduced-resolution overview, bit 2 = transparency mask.