LandsatLook images are full resolution files derived from Landsat Level 1 data products. The images are compressed and stretched to create an image optimized for image selection and visual interpretation. It is recommended that these images not be used in image analysis.
The files are included as options when downloading Landsat scenes from EarthExplorer (http://earthexplorer.usgs.gov), GloVis (http://glovis.usgs.gov) or the LandsatLook Viewer (http://landsatlook.usgs.gov) (See Figure 1).
LandsatLook download options
LandsatLook "Natural Color" Image:
The LandsatLook “Natural Color” image is a .jpg composite of three bands to show a “natural” looking (false color) image. Reflectance values were calculated from the calibrated scaled digital number (DN) image data. The reflectance values were scaled to a 1-255 range using a gamma stretch with a gamma=2.0. This stretch was designed to emphasize vegetation without clipping the extreme values.
- Landsat 8 OLI = Bands 6,5,4
- Landsat 7 ETM+ and Landsat 4-5 TM = Bands 5,4,3
- Landsat 4-5 MSS = Bands 2,4,1
- Landsat 1-3 MSS = Bands 7,5,4
LandsatLook “Thermal" Image:
The LandsatLook “Thermal” image is a one-band gray scale .jpg image to display thermal properties of the scene. Image brightness temperature values were calculated from the calibrated scaled digital number (DN) image data. An image specific 2 percent clip and a linear stretch to 1-255 were applied to the brightness temperature values.
- Landsat 8 TIRS = Band 10
- Landsat 7 ETM+ = Band 61-high gain
- Landsat 4-5 TM = Band 6
- Landsat 1-5 MSS = not available
LandsatLook “Quality” Image (Landsat 8 only):
The LandsatLook “Quality” image is an 8-bit .png image generated from the Landsat 8 16-bit quality band. This file includes values representing bit-packed combinations of surface, atmosphere, and sensor conditions that can affect the overall usefulness of a given pixel. The color mapping assignments can be seen in Table 1 below.
|8-Bit LandsatLook QA Band - Read bits from RIGHT to LEFT <- starting with Bit 0
|*Set for highest confidence value (11)
Table 1: “Quality” Band bit mapping assignments
LandsatLook Images with Geographic Reference:
The LandsatLook image option with Geographic Reference is a .zip file bundle that contains the “Natural Color” and gray-scale “Thermal” image browse products in georeferenced GeoTiff (.tif) format for Landsat 1-7 data. Landsat 8 scenes are being transitioned, and will contain either the .tif or .jpg files. The file package also includes the 8-bit “Quality” image in .png format (for Landsat 8 only).
LandsatLook “Natural Color” Image: Landsat 8 Path 45 Row 30 Acquired April 23, 2013
LandsatLook “Thermal” Image: Landsat 8 Path 45 Row 30 Acquired April 23, 2013
LandsatLook “Quality” Image: Landsat 8 Path 45 Row 30 Acquired April 23, 2013 with background color set to dark grey.
Additional Information about LandsatLook .jpg images:
Many geographic information systems and image processing software packages easily support .jpg images. To create these files, Landsat data is mapped to a 1-255 range, with the fill area set to zero (if a no-data value is set to zero, the compression algorithm may introduce zero-value artifacts into the data area causing very dark data values to be displayed as no-data.)