ImageMagick Image libraries

The ImageMagick libraries distributed with EMu are stored under the same directory as the program executable. If a network installation is performed, the libraries reside on a server machine in a directory accessible to all client machines. In the case of a standalone installation, they are installed on the local machine. The libraries do not require any registration with Windows (that is, they are not COM objects). The directory structure is:

where:

• ImageMagick Core Libraries provide the core image functionality (e.g. resizing code, etc.) and Configuration Files contains language specific text and other configuration files. These files do not need to be modified.
• Image Reader/Writers is a collection of files used to read and write specific image formats. For example, IM_MOD_RL_jpeg_.dll is used to read and write JPEG files.
• Image Filters are used to provide statistical information about images (not used by EMu).

By default EMu installs ImageMagick's 16 bit libraries. These libraries are capable of storing 16 bits of colour information per colour channel, that is:

• 48 bits per pixel for RGB images
• 64 bits per pixel for CMYK

Most images produced until recently (2007) only store 8 bits of colour information per colour channel, but newer digital devices are now capable of producing 16 bit images that give a greater colour range, resulting in "truer" colour pictures. It is to cater for these images that EMu distributes the 16 bit libraries.

Note: 8 bit images can be read and manipulated by the 16 bit libraries without any loss of definition.

There is however an overhead associated with providing support for 16 bit images. When ImageMagick reads an image it decodes the file format (via a coder) and stores it in an uncompressed pixel format in memory. Each pixel uses 64 bits or 8 bytes regardless of the number of bits per pixel in the image file. If an image which is 1000 pixels by 1000 pixels is read, the memory required to hold the image is 8 Mb (1000 * 1000 * 8 bytes). If a 5000 pixel by 5000 pixel image is read however, 200 Mb is required (5000 * 5000 * 8 bytes) even if it is a monochrome image!

Note: Unless there is at least 1 Gb of memory installed, a computer will slow down considerably when dealing with such images. Therefore before manipulating large images, it will be worth confirming that there is sufficient computer memory to manipulate the images.

EMu loads the ImageMagick libraries dynamically the first time that are required. This means that EMu determines where the libraries are installed (in the same directory as the EMu executable by default) and having done so "loads" them into memory. In order to locate the libraries EMu first looks up the MAGICK_HOME environment variable. If it is set, EMu will attempt to load the ImageMagick libraries from the directory specified by the environment variable. If the environment variable is not set, EMu will look under the executable directory.

It is possible to take advantage of the MAGICK_HOME environment variable to force EMu to load a different version of the ImageMagick libraries than the ones distributed with EMu. For instance, to halve memory usage and load images 33% faster, it is possible to use the 8 bit ImageMagick libraries.

Note: By doing so however, it will not be possible to view or read 16 bit images.

To bypass the libraries distributed with EMu:

1. Install the required version of ImageMagick on your local machine or network server. You can download the releases from http://www.imagemagick.org/script/download.php. Be sure to download the DLL version, not the static version.
2. Run Start>Control Panel>System and select the Advanced tab.
3. Click the Environment Variables button.
4. Under User variables for..., click the New button.
5. Enter MAGICK_HOME for the Variable name and set the Variable value to the directory into which ImageMagick was installed:

   

6. Click the OK button to save the setting.

Now, when EMu loads the ImageMagick libraries it will load those under the specified directory.

Note: Use this technique to install later releases of the libraries that may support more image formats (although the libraries distributed with EMu will be updated on a regular basis).

If your organisation does not want to use the 16 bit libraries and you have a network installation, copy the contents of the 8 bit image directory over the ImageMagick directory under the EMu executable directory. Using this technique it is not necessary to set the MAGICK_HOME environment variable.

Note: Note however that the next upgrade you perform will replace your libraries with the 16 bit versions, so it will be necessary to perform the copy again.

If EMu cannot load the ImageMagick libraries, the following error dialogue is displayed:

If you have set the MAGICK_HOME environment variable, this error indicates that one of the following conditions is not true:

• The environment variable value must contain the path to an existing directory.
• As a minimum the user must have the ability to list files in the specified directory.
• A valid set of ImageMagick libraries, including a config and modules directory and a series of DLL files must exist in the specified directory.
• All DLLs in the specified directory and modules/coders must have Read and Execute permission for the current user.
• As a minimum all directories below the specified directory (namely config. modules. modules/coders and modules/filters) must have List Files permission.
• As a minimum all configuration files in config must have Read permission.

ImageMagick uses delegates to provide support for certain image formats. A delegate is a piece of software that converts the image format into a format that ImageMagick can handle. EMu bundles two delegates with the ImageMagick libraries:

• dcraw.exe (handles digital camera RAW format)
• hp2xx.exe (handles HPGL files).

If you try to import or generate an image format that requires a delegate and the delegate is not installed, an error dialogue similar to this one is displayed:

In order to determine the delegate required and to download the necessary software, visit the ImageMagick Formats (http://www.imagemagick.org/script/formats.php) page. Once the delegate software is installed the image format will be useable.

ImageMagick provides support for a large number of image formats. The actual list of file types supported depends on the version of ImageMagick installed. When EMu needs to display a list of supported image formats (either for adding an image or generating a derivative) it asks ImageMagick for a list of file formats that have coders. EMu then consults the Windows registry to determine whether each entry in the list has a MIME type of image, discarding entries that do not. Thus if an installed application handles a given image format, EMu will add it to the list of available Image Files. Finally, the image format must have an encoder (used to write the format) and a decoder (used to read the format).

The list of image formats supported is:

File Extension	Coder	Read/ Write/ Multi-page	Format
A	RAW	rw+	Raw alpha samples
AVS	AVS	rw+	AVS X image
B	RAW	rw+	Raw blue samples
BIE	JBIG	rw-	Joint Bi-level Image experts Group interchange format (1.5)
BMP	BMP	rw-	Microsoft Windows bitmap image
C	RAW	rw+	Raw cyan samples
CIN	CIN	rw+	Cineon Image File
CMYK	CMYK	rw+	Raw cyan, magenta, yellow, and black samples
CMYKA	CMYK	rw+	Raw cyan, magenta, yellow, black, and opacity samples
CUR	CUR	rw-	Microsoft icon
CUT	CUT	r--	DR Halo
DCM	DCM	r--	Digital Imaging and Communications in Medicine image
DCX	PCX	rw+	ZSoft IBM PC multi-page Paintbrush
DNG	DNG	r--	Digital Negative
EMF	WMF	r--	Windows WIN32 API rendered Enhanced Meta File
EPDF	PDF	rw-	Encapsulated Portable Document Format
EPI	PS	rw-	Encapsulated PostScript Interchange format
EPS	PS	rw-	Encapsulated PostScript
EPSF	PS	rw-	Encapsulated PostScript
EPSI	PS	rw-	Encapsulated PostScript Interchange format
EPT	EPT	rw-	Encapsulated PostScript with TIFF preview
EPT2	EPT	rw-	Encapsulated PostScript Level II with TIFF preview
EPT3	EPT	rw+	Encapsulated PostScript Level III with TIFF preview
FAX	FAX	rw+	Group 3 FAX
FITS	FITS	rw-	Flexible Image Transport System
FTS	FTS	rw-	Flexible Image Transport System
G	RAW	rw+	Raw green samples
G3	FAX	rw-	Group 3 FAX
GIF	GIF	rw+	CompuServe graphics interchange format
GIF87	GIF	rw-	CompuServe graphics interchange format (version 87a)
GRAY	GRAY	rw+	Raw gray samples
ICB	TGA	rw+	Truevision Targa image
ICO	ICON	rw-	Microsoft icon
ICON	ICON	rw-	Microsoft icon
JBG	JBIG	rw+	Joint Bi-level Image experts Group interchange format (1.5)
JBIG	JBIG	rw+	Joint Bi-level Image experts Group interchange format (1.5)
JNG	PNG	rw-	JPEG Network Graphics
JP2	JP2	rw-	JPEG-2000 File Format Syntax
JPC	JPC	rw-	JPEG-2000 Code Stream Syntax
JPEG	JPEG	rw-	Joint Photographic Experts Group JFIF format (62)
JPG	JPEG	rw-	Joint Photographic Experts Group JFIF format
JPX	JPX	rw-	JPEG-2000 File Format Syntax
K	RAW	rw+	Raw black samples
M	RAW	rw+	Raw magenta samples
MAP	MAP	rw-	Colormap intensities and indices
MAT	MAT	rw+	MATLAB image format
MIFF	MIFF	rw+	Magick Image File Format
MNG	PNG	rw+	Multiple-image Network Graphics (libpng 1.2.8)
MONO	MONO	rw-	Bi-level bitmap in least-significant-byte first order
MPC	MPC	rw+	Magick Persistent Cache image format
MSL	MSL	rw+	Magick Scripting Language
MTV	MTV	rw+	MTV Raytracing image format
MVG	MVG	rw-	Magick Vector Graphics
O	RAW	rw+	Raw opacity samples
OTB	OTB	rw-	On-the-air bitmap
PAL	UYVY	rw-	16bit/pixel interleaved YUV
PALM	PALM	rw+	Palm pixmap
PAM	PNM	rw+	Common 2-dimensional bitmap format
PBM	PNM	rw+	Portable bitmap format (black and white)
PCD	PCD	rw-	Photo CD
PCDS	PCD	rw-	Photo CD
PCL	PCL	rw-	Printer Control Language
PCT	PICT	rw-	Apple Macintosh QuickDraw/PICT
PCX	PCX	rw-	ZSoft IBM PC Paintbrush
PDB	PDB	rw+	Palm Database ImageViewer Format
PDF	PDF	rw+	Portable Document Format
PGM	PNM	rw+	Portable graymap format (gray scale)
PGX	PGX	r--	JPEG-2000 VM Format
PICON	XPM	rw-	Personal Icon
PICT	PICT	rw-	Apple Macintosh QuickDraw/PICT
PIX	PIX	r--	Alias/Wavefront RLE image format
PJPEG	JPEG	rw-	Progressive Joint Photographic Experts Group JFIF
PNG	PNG	rw-	Portable Network Graphics (libpng 1.2.8)
PNG24	PNG	rw-	24-bit RGB PNG, opaque only (zlib 1.2.3)
PNG32	PNG	rw-	32-bit RGBA PNG, semitransparency OK
PNG8	PNG	rw-	8-bit indexed PNG, binary transparency only
PNM	PNM	rw+	Portable anymap
PPM	PNM	rw+	Portable pixmap format (color)
PS	PS	rw+	PostScript
PSD	PSD	rw+	Adobe Photoshop bitmap
PTIF	TIFF	rw-	Pyramid encoded TIFF
PWP	PWP	r--	Seattle Film Works
R	RAW	rw+	Raw red samples
RAS	SUN	rw+	SUN Rasterfile
RGB	RGB	rw+	Raw red, green, and blue samples
RGBA	RGB	rw+	Raw red, green, blue, and alpha samples
RGBO	RGB	rw+	Raw red, green, blue, and opacity samples
RLA	RLA	r--	Alias/Wavefront image
RLE	RLE	r--	Utah Run length encoded image
SCR	SCR	r--	ZX-Spectrum SCREEN$
SCT	SCT	r--	Scitex HandShake
SFW	SFW	r--	Seattle Film Works
SGI	SGI	rw+	Irix RGB image
STEGANO	STEGANO	r--	Steganographic image
SUN	SUN	rw+	SUN Rasterfile
SVG	SVG	rw+	Scalable Vector Graphics (XML 2.4.19)
SVGZ	SVG	rw+	Compressed Scalable Vector Graphics (XML 2.4.19)
TEXT	TXT	rw+	Text
TGA	TGA	rw+	Truevision Targa image
TIFF	TIFF	rw+	Tagged Image File Format (LIBTIFF, Version 3.8.2)
TIM	TIM	r--	PSX TIM
TXT	TXT	rw+	Text
UYVY	UYVY	rw-	16bit/pixel interleaved YUV
VDA	TGA	rw+	Truevision Targa image
VICAR	VICAR	rw-	VICAR rasterfile format
VID	VID	rw+	Visual Image Directory
VIFF	VIFF	rw+	Khoros Visualisation image
VST	TGA	rw+	Truevision Targa image
WBMP	WBMP	rw-	Wireless Bitmap (level 0) image
WMF	WMF	r--	Windows Meta File
WMFWIN32	WMFWIN32	r--	Windows WIN32 API rendered Meta File
WMZ	WMZ	r--	Compressed Windows Meta File
WPG	WPG	r--	Word Perfect Graphics
X	X	rw+	X Image
XBM	XBM	rw-	X Windows system bitmap (black and white)
XC	XC	r--	Constant image uniform colour
XCF	XCF	r--	GIMP image
XPM	XPM	rw-	X Windows system pixmap (colour)
XV	VIFF	rw+	Khoros Visualization image
XWD	XWD	rw-	X Windows system window dump (colour)
Y	RAW	rw+	Raw yellow samples
YCbCr	YCbCr	rw+	Raw Y, Cb, and Cr samples
YCbCrA	YCbCr	rw+	Raw Y, Cb, Cr, and opacity samples
YUV*	YUV	rw-	CCIR 601 4:1:1 or 4:2:2

where:

r	indicates the format can be read (that is decoded)
w	indicates the format can be written (that is encoded)
+	indicates the format handles multi-page images

The default list of image formats supported by EMu is:

• BMP - Microsoft Windows Bitmap Image
• DCX - ZSoft IBM PC multi-page Paintbrush
• GIF - CompuServe Graphics Interchange Format
• JP2 - JPEG 2000
• JPEG - Joint Photographic Experts Group
• PCD - Photo CD
• PCX - ZSoft IBM PC Paintbrush
• PNG - Portable Network Graphics
• TGA - Truevision Targa Image
• TIFF - Tagged Image File Format

However, the list is typically longer, depending on the software installed on a computer.