Configuration Options

Some functionality of large_image is controlled through configuration parameters. These can be read or set via python using functions in the large_image.config module, getConfig and setConfig.

Configuration parameters:

  • logger: a Python logger. Most log messages are sent here.

  • logprint: a Python logger. Messages about available tilesources are sent here.

  • cache_backend: either python (the default) or memcached, specifying where tiles are cached. If memcached is not available for any reason, the python cache is used instead.

  • cache_python_memory_portion: If tiles are cached in python, the cache is sized so that it is expected to use less than 1 / (cache_python_memory_portion) of the available memory. This is an integer.

  • cache_memcached_url: If tiles are cached in memcached, the url or list of urls where the memcached server is located. Default ‘’.

  • cache_memcached_username: A username for the memcached server. Default None.

  • cache_memcached_password: A password for the memcached server. Default None.

  • cache_tilesource_memory_portion: Tilesources are cached on open so that subsequent accesses can be faster. These use file handles and memory. This limits the maximum based on a memory estimation and using no more than 1 / (cache_tilesource_memory_portion) of the available memory.

  • cache_tilesource_maximum: If this is non-zero, this further limits the number of tilesources than can be cached to this value.

  • cache_sources: If set to False, the default will be to not cache tile sources. This has substantial performance penalties if sources are used multiple times, so should only be set in singular dynamic environments such as experimental notebooks.

  • max_small_image_size: The PIL tilesource is used for small images if they are no more than this many pixels along their maximum dimension.

  • source_bioformats_ignored_names, source_pil_ignored_names, source_vips_ignored_names: Some tile sources can read some files that are better read by other tilesources. Since reading these files is suboptimal, these tile sources have a setting that, by default, ignores files without extensions or with particular extensions. This setting is a Python regular expressions. For bioformats this defaults to r'(^[!.]*|\.(jpg|jpeg|jpe|png|tif|tiff|ndpi))$'.

  • icc_correction: If this is True or undefined, ICC color correction will be applied for tile sources that have ICC profile information. If False, correction will not be applied. If the style used to open a tilesource specifies ICC correction explicitly (on or off), then this setting is not used. This may also be a string with one of the intents defined by the PIL.ImageCms.Intents enum. True is the same as perceptual.

  • max_annotation_input_file_length: When an annotation file is uploaded through Girder, it is loaded into memory, validated, and then added to the database. This is the maximum number of bytes that will be read directly. Files larger than this are ignored. If unspecified, this defaults to the larger of 1 GByte and 1/16th of the system virtual memory.

Configuration from Python

As an example, configuration parameters can be set via python code like:

import large_image

large_image.config.setConfig('max_small_image_size', 8192)

Configuration from Environment

All configuration parameters can be specified as environment parameters by prefixing their uppercase names with LARGE_IMAGE_. For instance, LARGE_IMAGE_CACHE_BACKEND=python specifies the cache backend. If the values can be decoded as json, they will be parsed as such. That is, numerical values will be parsed as numbers; to parse them as strings, surround them with double quotes.

Configuration within the Girder Plugin

For the Girder plugin, these can also be set in the girder.cfg file in a large_image section. For example:

# cache_backend, used for caching tiles, is either "memcached" or "python"
cache_backend = "python"
# 'python' cache can use 1/(val) of the available memory
cache_python_memory_portion = 32
# 'memcached' cache backend can specify the memcached server.
# cache_memcached_url may be a list
cache_memcached_url = ""
cache_memcached_username = None
cache_memcached_password = None
# The tilesource cache uses the lesser of a value based on available file
# handles, the memory portion, and the maximum (if not 0)
cache_tilesource_memory_portion = 8
cache_tilesource_maximum = 0
# The PIL tilesource won't read images larger than the max small images size
max_small_image_size = 4096
# The bioformats tilesource won't read files that end in a comma-separated
# list of extensions
source_bioformats_ignored_names = r'(^[!.]*|\.(jpg|jpeg|jpe|png|tif|tiff|ndpi))$'
# The maximum size of an annotation file that will be ingested into girder
# via direct load
max_annotation_input_file_length = 1 * 1024 ** 3

Logging from Python

The log levels can be adjusted in the standard Python manner:

import logging
import large_image

logger = logging.getLogger('large_image')

Alternately, a different logger can be specified via setConfig in the logger and logprint settings:

import logging
import large_image

logger = logging.getLogger(__name__)
large_image.config.setConfig('logger', logger)
large_image.config.setConfig('logprint', logger)