You can use raster storage environments to adjust the default compression type, the default settings for pyramid creation and calculating statistics, the default tile size, the default resampling method, and the NoData mapping method to be used by geoprocessing tools that work with rasters.
Extension toolboxes such as 3D Analyst, Geostatistical Analyst, and ArcGIS Image Analyst do not honor all raster storage settings. Refer to the help topic for each tool for specifics on which environments are honored.
Not all environments apply to all storage types. Refer to the Raster storage matrix below for details. File Group 2 consists of ERDAS IMAGINE files. All remaining ArcGIS-supported raster file formats fall into File Group 1.
Raster storage matrix
| Storage setting | File Group 1 | File Group 2 | File Geodatabase | Enterprise Geodatabase |
|---|---|---|---|---|
Pyramids | yes OVR file | yes RRD type |
yes | yes |
Resampling | yes | yes |
yes | yes |
Levels | yes | yes |
yes | yes |
Skip first | yes | no | yes | yes |
Raster statistics | yes | yes |
yes | yes |
Skip factor | yes | yes |
yes | yes |
Ignore value | yes | yes |
yes | yes |
Compression | yes | yes RLE compression |
yes | yes |
LZ77 | yes | no |
yes | yes |
JPEG | yes | no |
yes | yes |
JPEG 2000 | yes | no |
yes | yes |
Tile size | TIFF only | no |
yes | yes |
Note:
Compression is dependent on the type of file format. See Raster file formats for the file formats that support compression.
File and enterprise geodatabases only support LZ77, JPEG, JPEG2000, and NONE compression types.
Pyramid environment
Pyramids are reduced-resolution representations of a dataset. They can speed up display of raster datasets by retrieving only the data that is necessary at a specified resolution. By default, pyramids are created for raster datasets by resampling the original data. There are three resampling methods available: nearest neighbor, bilinear, and cubic.
If you uncheck the Build pyramids check box, no pyramids will be created with the output raster. Not building pyramids saves storage space but leads to slower display speeds, especially for larger raster datasets.
You can skip the first pyramid level. Skipping the first pyramid level saves a bit of disk space but slows down the display when you are viewing small scales. Alternatively, you can define the number of levels, but this may affect the speed when viewing at a very large scale.
The default resampling method is nearest neighbor. This method works for any type of raster dataset. Use nearest neighbor for nominal data or raster datasets with color maps, such as land-use data, scanned maps, and pseudo color images. Use bilinear interpolation or cubic convolution for continuous data, such as satellite imagery or aerial photography.
If the raster pyramids are built as overviews (OVR), you can compress the pyramids with either LZ77 or JPEG. If the pyramids can only be built as a reduced-resolution dataset, no additional compression options are available.
Raster Statistics environment
The Raster Statistics environment allows you to build statistics for output raster datasets. Statistics are required for a raster dataset to perform certain tasks in ArcGIS AllSource, such as applying a contrast stretch or classifying data. It is not essential to build statistics if they have not been calculated, since they are calculated the first time they are needed. However, it is recommended that you calculate statistics for raster datasets before using them if you want to use certain features that require statistics. The default display of a raster is improved in most cases if statistics have been calculated, because a standard deviation stretch is applied if statistics are present.
Setting a skip factor allows you to speed up the process of calculating statistics by skipping pixels. The skip factor does not apply to Grid datasets.
Values you set to ignore do not participate in the statistics calculation. Typically, you can ignore the values of the background.
Compression environment
The Compression environment is used by tools with a raster dataset as output. There are nine compression methods available for geoprocessing tools. Of these compressions, four types of compression are supported when loading rasters to a geodatabase: LZ77, JPEG, JPEG 2000, and NONE.
Valid compressions for each pixel depth
| Compression | Pixel depth (8 bit) | Pixel depth (16 bit) | Additional information |
|---|---|---|---|
LZ77 | Yes | Yes | Any pixel depth. |
LERC | Yes | Yes | As pixel depth increases, so does the efficiency of the compression algorithm. |
JPEG | Yes | Only 12-bit data; stored as 16-bit data | |
JPEG_YCbCr | Yes | No | |
JPEG2000 | Yes | Yes | |
PackBits | Yes | No | 1-bit to 8-bit data. |
LZW | Yes | Yes | Any pixel depth. |
RLE | Yes | Yes | Any pixel depth. |
CCITT_G3 | No | No | Only for 1-bit data. |
CCITT_G4 | No | No | Only for 1-bit data. |
CCITT_1D | No | No | Only for 1-bit data. |
LZ77 (the default) is a lossless compression that preserves all raster cell values. It uses the same compression algorithm as the PNG image format and one similar to ZIP compression. Since pixels do not change their values when compressed, use LZ77 for performing visual or algorithmic analysis.
JPEG is a lossy compression and is used because raster cell values may not be preserved after compression and decompression. It uses the public domain JPEG (JFIF) compression algorithm and only works for unsigned 8-bit raster data (single-band grayscale or three-band raster data).
JPEG_YCbCr is a lossy compression using the luma (Y) and chroma (Cb and Cr) color space components.
JPEG 2000 uses wavelet technology to compress rasters, so they visually appear lossless, meaning that although the cell values are manipulated, the differences between the original and the same raster with compression are not easily distinguishable. Use JPEG or JPEG 2000 for rasters that are meant as pictures or backdrop imagery.
If JPEG or JPEG 2000 is selected, you can also set the compression quality to control how much loss the image is subjected to by the compression algorithm. The values of the pixels of an image compressed with a higher compression quality will be closer to those of the original image. Valid value ranges of compression quality for JPEG are from 5 to 95. Valid value ranges for JPEG 2000 are from 1 to 100. The default compression quality is 75. The amount of compression depends on the data and compression quality. The more homogeneous the data, the higher the compression ratio. The lower the compression quality, the higher the compression ratio. Lossy compression typically results in higher compression ratios when compared to lossless compression.
The primary benefits of compressing data are that compressed data requires less storage space and data display times will be quicker, as there is less information to transmit.
Tile Size environment
The Tile Size environment is used by tools that create raster datasets and are stored in blocks.
The default tile size is 128 by 128, which is appropriate for most cases. However, if the tile size is too big, you will bring up more data than is needed each time you access the data. For example, you want to display a window of 100 by 100 and it only covers one tile. If you set the tile size to 512, you need to get a tile of 512 by 512 pixels. If the tile size is set to 128 by 128, you'll bring up less extra data if the display window is 100 by 100.
Resampling Method environment
Resampling is the process of interpolating the pixel values while transforming a raster dataset. Resampling is used when the input and output do not line up exactly, when the pixel size changes, when the data is shifted, or a combination of these.
- Nearest—Performs a nearest neighbor assignment and is the fastest of the interpolation methods. It is used primarily for discrete data, such as a land-use classification, since it will not change the values of the cells. The maximum spatial error will be one-half the cell size.
- Bilinear—Performs a bilinear interpolation and determines the new value of a cell based on a weighted distance average of the four nearest input cell centers. It is useful for continuous data and will cause some smoothing of the data.
- Cubic—Performs a cubic convolution and determines the new value of a cell based on fitting a smooth curve through the 16 nearest input cell centers. It is appropriate for continuous data, although it may result in the output raster containing values outside the range of the input raster. If this is unacceptable, use Bilinear instead. The output from cubic convolution is geometrically less distorted than the raster achieved by running the nearest neighbor resampling algorithm. The disadvantage of the Cubic option is that it requires more processing time.
NoData environment
Use this environment when the NoData value from the input must be transferred to the output raster. This setting allows you to specify the value you use as the NoData value in the output.
- None—There will be no NoData value rules in place. If the input and the output have the same value range, the NoData value will be transferred over with no changes. However, if the value range changes, NoData will have no value in the output. This is the default method.
- Maximum—The maximum value in the output data range will be used as the NoData value.
- Minimum—The minimum value in the output data range will be used as the NoData value.
- Map values up—The lowest value in the range will be promoted and the lowest will become NoData. If the data is unsigned, the value of zero will become one, the NoData value will be zero, and the other values remain the same. If the data is signed, the lowest value in the range will be promoted and the lowest will become NoData. For example, with 8-bit signed integer data, -127 will become -126, and the NoData value will be -127.
- Map values down—The NoData value will be the maximum value in the data range, the highest value of the data range will become one value less, and the other values remain the same. For example, with 8-bit unsigned integer data, the NoData value will be 255, the value of 255 will become 254, and the other values will remain the same.
- Promotion—If there is a NoData value outside the input's data range, the pixel depth of the output will be promoted to the next available level, and NoData will take the maximum value in the new data range. For example, an 8-bit unsigned integer dataset that requires the 256 value to be NoData will be promoted to a 16-bit dataset and the maximum value will become NoData. If there is a NoData value within the input's data range to be written to the output or if there isn't any NoData, the pixel depth will not be promoted.
If there is a NoData value outside the input's data range, the pixel depth will be promoted to the next available level, and the NoData value will be the one specified. For example, an 8-bit unsigned integer dataset that requires 256 as NoData will be promoted to a 16-bit dataset and 256 becomes the NoData value. If the NoData value specified is within the input's data range, the pixel depth will not be promoted for the output.