ExportToJPEG

Zusammenfassung

Exports the page layout or data frame of a map document (.mxd) to the Joint Photographic Experts Group (JPEG) format.

Beschreibung

JPEG files are compressed image files. They support 24-bit color and can be substantially more compact than many other file types. The JPEG compression algorithm is lossy and is not as well suited for line drawings and other textual or iconic graphics, and thus the PNG and GIF formats are preferred for these types of images.

To export a single data frame instead of the entire page layout, pass a DataFrame object to the function's data_frame parameter. Because data frame exports do not have an associated page to provide height and width information, you must provide this via the df_export_width and df_export_height parameters.

Controlling graphic quality of the generated image differs for page layout exports versus data frame exports. When exporting a page layout, control image detail by changing the resolution parameter. When exporting a data frame, keep the resolution parameter at its default value, and change the df_export_width and df_export_height parameters to alter image detail. The height and width parameters directly control the number of pixels generated in the export file and are only used when exporting a data frame. Images with larger numbers of pixels will have higher image detail. For most page layout exports, the default parameter values should generate good results and nice looking export images on the first try. For data frame exports, you may need to experiment with the df_export_width and df_export_height values a few times before getting the result you want.

World files are not generated for page layout exports; a referenced data frame must be provided or the export will fail.

Refer to the Exporting your map topic in ArcGIS Help for more detailed discussions on exporting maps.

Syntax

ExportToJPEG (map_document, out_jpeg, {data_frame}, {df_export_width}, {df_export_height}, {resolution}, {world_file}, {color_mode}, {jpeg_quality}, {progressive})

Parameter	Erläuterung	Datentyp
map_document	A variable that references a MapDocument object.	MapDocument
out_jpeg	A string that represents the path and file name for the output export file.	String
data_frame	A variable that references a DataFrame object. Use the string/constant "PAGE_LAYOUT" to export the map document's page layout instead of an individual data frame. (Der Standardwert ist PAGE_LAYOUT)	Object
df_export_width	A number that defines the width of the export image in pixels for a data frame export. df_export_width is only used when exporting a data frame. Exporting a page layout uses the map document page width instead of df_export_width. (Der Standardwert ist 640)	Integer
df_export_height	A number that defines the height of the export image in pixels for a data frame export. df_export_height is only used when exporting a data frame. Exporting a page layout uses the map document page height instead of df_export_height. (Der Standardwert ist 480)	Integer
resolution	A number that defines the resolution of the export file in dots per inch (DPI). (Der Standardwert ist 96)	Integer
world_file	If set to True, a georeferenced world file is created. The file contains pixel scale information and real-world coordinate information. (Der Standardwert ist False)	Boolean
color_mode	This value specifies the number of bits used to describe color. 24-BIT_TRUE_COLOR —24-bit true color. 8-BIT_PALETTE —8-bit palette. 8-BIT_GRAYSCALE —8-bit grayscale. 1-BIT_MONOCHROME_MASK —1-bit monochrome mask. 1-BIT_MONOCHROME_THRESHOLD —1-bit monochrome threshold. (Der Standardwert ist 24-BIT_TRUE_COLOR)	String
jpeg_quality	This value (0–100) controls the amount of compression applied to the output image. For JPEG, image quality is adversely affected the more compression is applied. A higher quality (highest = 100) setting will produce sharper images and larger file sizes. A lower quality setting will produce more image artifacts and smaller files. (Der Standardwert ist 100)	Integer
progressive	If set to True, a progressive JPEG file will be created. A progressive image is one that displays in a series of scans of increasing quality rather than displaying the whole image at once. (Der Standardwert ist False)	Boolean

Codebeispiel

ExportToJPEG example 1

This script opens a map document and exports the page layout to a JPEG file using default values for all options.

import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
arcpy.mapping.ExportToJPEG(mxd, r"C:\Project\Output\Project.jpg")
del mxd

ExportToJPEG example 2

This script will export a single data frame instead of the entire page layout, similar to exporting from data view in the ArcMap application. The default values for df_export_width and df_export_height are 640 and 480. By passing larger values for these parameters, we are able to produce an output image with higher detail. Setting world_file = True generates a georeferenced world file in the same directory as the output file.

import arcpy
mxd = arcpy.mapping.MapDocument(r"C:\Project\Project.mxd")
df = arcpy.mapping.ListDataFrames(mxd, "Transportation")[0]
arcpy.mapping.ExportToJPEG(mxd, r"C:\Project\Output\ProjectDataFrame.jpg", df,
                           df_export_width=1600,
                           df_export_height=1200,
                           world_file=True)
del mxd