PCX File Format Summary

Also Known As:

PC Paintbrush File Format, DCX, PCC

Type Bitmap
Colors Mono, 4-bit, 8-bit, 24-bit
Compression RLE, uncompressed
Maximum Image Size 64Kx64K pixels
Multiple Images Per File No
Numerical Format Little-endian
Originator ZSoft, Microsoft
Platform MS-DOS, Windows, UNIX, others
Supporting Applications Too numerous to list
See Also FAX formats

PCX is used in Microsoft Windows and Windows-based products but has found wide acceptance mainly in the MS-DOS world. It is mainly an exchange and storage format.

A partially documented format in wide use, which is quick and easy to read and decompress. It lacks, however, a superior compression scheme, making it unsuitable for the storage of deep-pixel images.

Vendor specifications are available for this format.

Code fragments are available for this format.

Sample images are available for this format.

PCX is one of the most widely used storage formats. It originated with ZSoft's MS-DOS-based PC Paintbrush, and because of this, PCX is sometimes referred to as the PC Paintbrush format. ZSoft entered into an OEM arrangement with Microsoft, which allowed Microsoft to bundle PC Paintbrush with various products, including a version called Microsoft Paintbrush for Windows; this product was distributed with every copy of Microsoft Windows sold. This distribution established the importance of PCX, not only on Intel-based MS-DOS platforms, but industry-wide.

File Organization
File Details
For Further Information

PCX has been used by manufacturers of computer-based FAX boards and also as a general format for the storage of clip art targeted at the desktop publishing aftermarket.

The original PCX format (starting with v2.5 of PC Paintbrush) stored graphics and images with no more than 16 colors, due to the limitations of Enhanced Graphics Adapter (EGA) display technology produced by IBM. When IBM introduced the Virtual Graphics Array (VGA) display adapter, the PCX format was revised to store graphics and images with up to 256 colors.

The latest revision of the PCX format now includes the ability to store 24-bit color images. This allows the PCX format to be used for the storage of images created by the most advanced graphics, imaging, and video technology available today.

PCX is hardware-dependent in the sense that it was originally designed to accommodate a specific type of display hardware. Data may be stored either plane- or pixel-oriented, to accommodate the hardware design of the plane-oriented IBM EGA or the pixel-oriented IBM VGA display adapters.

Image data is encoded using an RLE variant, which is simple and somewhat quick in its operation, if not terribly efficient in actually reducing the size of the data. As with other RLE schemes, how much the PCX compression scheme reduces the size of a given image is difficult to say, because the reduction factor is dependent largely upon the content of the image (how "busy" the image is) and how many colors are actually used. Generally, an image incorporating 16 or fewer colors will be reduced by 40 to 70 percent from the original data, whereas a 64- to 256-color image from a scanner or video source may be reduced by only 10 to 30 percent. It is possible for an image to be so complex that the PCX compression scheme actually causes the data to increase in size after compression. (For further discussion of these and other topics, please see Chapter 9, Data Compression.)

File Organization

PCX files are organized into three major sections: the header, the image data, and the color palette. The color palette normally contains entries for 256 colors and is associated with the VGA display adapter. This VGA color palette is only found in later versions of the PCX image file format.

File Details

This section describes the major sections of PCX files and methods of reading, compressing, encoding, and decoding these files.


The first 128 bytes of every PCX file is the header, which has the following format:

typedef struct _PcxHeader
  BYTE	Identifier;        /* PCX Id Number (Always 0x0A) */
  BYTE	Version;           /* Version Number */
  BYTE	Encoding;          /* Encoding Format */
  BYTE	BitsPerPixel;      /* Bits per Pixel */
  WORD	XStart;            /* Left of image */
  WORD	YStart;            /* Top of Image */
  WORD	XEnd;              /* Right of Image
  WORD	YEnd;              /* Bottom of image */
  WORD	HorzRes;           /* Horizontal Resolution */
  WORD	VertRes;           /* Vertical Resolution */
  BYTE	Palette[48];       /* 16-Color EGA Palette */
  BYTE	Reserved1;         /* Reserved (Always 0) */
  BYTE	NumBitPlanes;      /* Number of Bit Planes */
  WORD	BytesPerLine;      /* Bytes per Scan-line */
  WORD	PaletteType;       /* Palette Type */
  WORD	HorzScreenSize;    /* Horizontal Screen Size */
  WORD	VertScreenSize;    /* Vertical Screen Size */
  BYTE	Reserved2[54];     /* Reserved (Always 0) */

Identifier is an identification value defined by the PCX specification as always being 10h. This value has no real meaning other than to indicate that the file is a ZSoft PCX file. PCX readers should always check that this byte contains the proper value, even though the file may have the extension PCX. However, it is possible that a non-PCX format file might also begin with the value 10h, so the remainder of the header information should be read, and the information fields be checked for the proper values before trying to decode any image data in the file. In other words, don't just jump to byte offset 128 and start decoding what you think is encoded image data.

Version contains the version of Paintbrush that created the PCX file. ZSoft has released updated revisions of the PCX format to keep up with the increasing functionality of its PC Paintbrush program and the burgeoning display adapter technology available for the PC. Each PCX file version has separate requirements for handling and displaying its image. Prior to v2.5 of PC Paintbrush, the PCX image file format was considered proprietary information by ZSoft Corporation.

Possible values for Version are shown as follows:


PC Paintbrush Version and Description


Version 2.5 with fixed EGA palette information


Version 2.8 with modifiable EGA palette information


Version 2.8 without palette information


PC Paintbrush for Windows


Version 3.0 of PC Paintbrush, PC Paintbrush Plus, PC Paintbrush Plus for Windows, Publisher's Paintbrush, and all 24-bit image files

Encoding indicates the type of encoding used on the image data. The only encoding algorithm currently supported by the PCX specification is a simple byte-wise run-length encoding (RLE) scheme indicated by a value of 1 in this byte. It would seem to follow that if a PCX file held unencoded image data this value would be 0. PCX files, however, always contain encoded image data, and currently the only valid value for the encoding field is 1.

BitsPerPixel is the number of bits per pixel per plane in the image data. The possible values are 1, 2, 4, and 8 for 2-, 4-, 16-, and 256-color images. The planar data in a scan line is often padded with extra data to align the scan line on an even byte boundary to prevent aliasing (the "jaggies"). PCX paint and conversion programs use this value to find where in a scan line pixel data stops and extra padding begins.

XStart, YStart, XEnd, and YEnd store the size of the image in pixels. These four values are the rectangular dimensions of the visible part of the PCX image (sometimes called the picture dimension window) and its position relative to the physical display screen. Using these dimensions, the largest PCX image that can be stored is 65,535x65,535 pixels in size. The dimensions are the location of the upper-left and lower-right corners of the PCX image on the display screen. The upper-left corner of the screen is considered to be at location 0,0, and any PCX image with an XStart and YStart of 0 will start displaying at this location. If the XStart and YStart are values greater than zero, then a display program should start displaying the PCX image starting at those pixel coordinates. However, this is a feature rarely supported by PCX display programs.

Any PCX image may contain extra bytes of padding at the end of each scan line or extra scan lines added to the bottom of the image. To prevent this extra data from becoming visible, only the image data within the picture dimension window coordinates is displayed.

HorzRes and VertRes are the horizontal and vertical size of the stored image in pixels per line or dots per inch (DPI). Scanned images have the DPI value of the device that created them. Typical DPI values for a scanned image may be 100x100 DPI or 300x300 DPI. An image produced by a FAX card can have a resolution of 100x200 DPI or 200x200 DPI. Images created by paint or screen dump programs will have pixel resolution values that reflect the resolution of the display mode under which they were created. For example, a typical VGA paint program saves images with a horizontal resolution of 320 pixels and a vertical resolution of 200 pixels. However, these values are not used when decoding image data.

Palette is a 48-byte array of 8-bit values that make up a 16-color EGA color palette. The earliest version of PC Paintbrush was not able to use a modifiable EGA palette and, therefore, used only the standard palette of the EGA. Subsequent versions have allowed the use of a modifiable palette enabling a PCX image file writer to choose which 16 (or fewer) of the 64 colors available to the EGA to use.

Reserved1 is not currently used and should have a value of 00h. Older versions of PCX used this field for file identification or to hold the mode value of the display screen on which the PCX image was created. Several paint and graphics display programs will, in fact, claim that a PCX file is invalid if this field is not set to 00h.

NumBitPlanes is the number of color planes that contains the image data. The number of planes is usually 1, 3, or 4 and is used in conjunction with the BitsPerPixel value to determine the proper video mode in which to display the image. PCX video display modes are shown as follows:

Bits per Pixel


Color Planes

per Plane

Number of Colors

Video Mode




















Extended VGA




Extended VGA and XGA

NumBitPlanes is also used to determine the maximum number of colors a PCX image may have. The number of bits per pixel per plane is multiplied by the number of color planes and shifted to the left by one:

MaxNumberOfColors = (1L << (BitsPerPixel * NumBitPlanes));

BytesPerLine is a 16-bit value indicating the size in bytes of a color plane in an unencoded scan line. This value may be multiplied by the NumBitPlanes value to find the total length of an unencoded scan line in bytes:

ScanLineLength = (BytesPerLine * NumBitPlanes);

PaletteType contains an indicator of information held in the color palette. A value of 1 indicates color or monochrome information, while a 2 indicates gray-scale information. This value is actually an indicator of whether the image should be displayed in color or gray-scale. (Only VGA is capable of displaying true gray-scale images.) PC Paintbrush and most other programs that use PCX files ignore this value.

HorzScreenSize and VertScreenSize were added to the PCX format starting with PC Paintbrush 4.0 and 4.0 Plus. These horizontal and vertical screen-size values represent the resolution of the screen on which the image was created. This allows graphics display programs to adjust their video mode to allow for proper display of the PCX image. Because these fields were added after the release of PC Paintbrush 3.0, there is no way to know if these fields contain valid information or are part of the Reserved2 field. Therefore, always check these values to be sure they are reasonable before you use them.

Reserved2 is the last field in the header and is a run of bytes with the value 00h. This filler field is used to pad the header out to a full 128 bytes and to save room for additional fields that might be added to the header in future revisions of the PCX format. The size of this field will be either 54 or 58 bytes, depending on whether or not the header contains the HorizScreenSize and VertScreenSize fields.


The color palette information within a PCX file varies depending upon the version of the PCX file.

16-color EGA palette

The first version of the PCX format did not support a modifiable color palette, so the values of the standard EGA color palette were always used. Later versions of PC Paintbrush could work with or without a modifiable palette, so two more versions of the PCX format appeared, one with palette information (modifiable palette) and one without palette information (standard EGA palette).

The EGA palette is a 48-byte array of 16 RGB triples. Each color triple contains a red, green, and blue value, each with a range of 0 to 255. The palette will contain entries for 2, 4, 8, or 16 color triples with any remaining entries being set to 00h. No interpretation is necessary for display adapters using this format of color values. The EGA, however, has only four possible values for each RGB color (0 through 3), so each RGB value is shifted to the right by six to obtain the proper value. To extract the proper values to load into the EGA palette registers, the following code is used:

EgaColor0Red   = EgaPalette[0] >> 6;
EgaColor0Green = EgaPalette[1] >> 6;
EgaColor0Blue  = EgaPalette[2] >> 6;
EgaColor1Red   = EgaPalette[3] >> 6;
EgaColor1Green = EgaPalette[4] >> 6;
EgaColor1Blue  = EgaPalette[5] >> 6;

4-color CGA palette

The EGA color palette is also used for displaying CGA images. Two- or four-color images may be displayed on the CGA using one of eight possible color palettes, each consisting of three foreground colors and one background color.

The most significant four bits of the first byte of the EGA color palette contains the background color and is in the range of 0 to 15.

The most significant three bits of the fourth byte of the color palette contains the foreground color. The three bits of the foreground color correspond to the Color Burst Enable, Palette, and Intensity settings of the CGA, as shown below.

Color Burst Enable



(Bit 7)

(Bit 6)

(Bit 5)

0 (color)

0 (yellow)

0 (normal)

1 (monochrome)

1 (white)

1 (bright)

Code used to extract the CGA color-level data from the EGA color palette is shown below:

/* Get the CGA background color */
CgaBackgroundColor  = EgaPalette[0] >> 4;   /* 0 to 15 */
/* Get the CGA foreground palette */
CgaColorBurstEnable = (EgaPalette[3] & 0x80) >> 7;  /* 0 or 1 */
CgaPaletteValue     = (EgaPalette[3] & 0x40) >> 6;  /* 0 or 1 */
CgaIntensityValue   = (EgaPalette[3] & 0x20) >> 5;  /* 0 or 1 */

256-color VGA palette

When PCX was conceived, the EGA was the premium display adapter available from IBM for the PC. The EGA could display only 16 colors from a palette of 64, so PCX was originally designed with a color palette large enough to hold only 16 colors.

The 16-color EGA technology of 1984, however, gave way to the 256-color VGA technology of 1987. PCX now fell short of VGA standard images that could contain up to 256 colors from a palette of 262,144, and a new color palette needed to be added to the PCX file format for VGA images. Because there was not enough room in the header for it, the designers of the PCX format appended it to the end of the PCX file itself.

This unconventional, if not inconvenient, location for the VGA palette presents a problem; because the size of the image data varies, the location of the VGA palette is different for every file. The position of the palette must be determined by its offset from the end of the file rather than from the beginning.

To see if a VGA palette is attached to a file, seek backwards 769 bytes from the end of the file. If the byte at this location is set to value C0h, then the 768 bytes following this value constitute a VGA color palette. The PCX specification states that if the version number in the header (byte 1) is 5 (v3.0), then there might be a VGA color palette attached.

Normally, a PCX file must have a VGA color palette attached only if there are more than 16 colors in the image; otherwise the EGA palette can be used. However, many graphics programs create v3.0 PCX image files without a VGA color palette, while other programs always attach a VGA color palette, even for 2-color images. To confuse things even more, 24-bit PCX images are always marked as v3.0, yet never have an attached color palette.

A v3.0 PCX image might not have a color palette; the value 768 bytes from the end of the file might be 0Ch by coincidence. In this rare case, a PCX reader would interpret the last 768 bytes of the encoded image data as a VGA palette, so a truly bizarre displayed image would result. One solution to this problem would be to first read all the image data and note whether the file pointer stopped 769 bytes from the end of the file. If so, then a VGA color palette is present. Another method would be to check the three bytes following the 0Ch value. This is the first color of the color palette and is normally black, so the three bytes following the suspect VGA palette indicator value should all be zero.

When a VGA palette is present in the file, its information is always used to display the image data, rather than using any information that may be present in the EGA color palette. If the colors in an image do not display correctly, it may be necessary to disable the color palette so the display hardware may use its native color palette. Disabling the color palette is accomplished by changing the version number in the header (byte 1) from 5 to 3. The display software should recognize that this version of the format has no color palette and, therefore, should use its own default palette.

The VGA palette itself is an array of 768 bytes (256x3) containing the red, green, and blue values for each of the 256 possible colors in a VGA PCX image. Color values are organized into triples, as in the EGA palette. Bytes 0, 1, and 2 are the red, green, and blue values for the color 0; bytes 3, 4, and 5 are the red, green, and blues values for color 1; and so on. Each RGB value is in the range of 0 to 255.

In fact, the VGA palette is simply a much longer version of the EGA palette. VGA display devices, however, require that palette color values be in the range of 0 to 63, so all RGB values should be divided by four (shifted to the right twice). VGA images may have 2-, 4-, 8-, 16-, 32-, 64-, 128-, or 256-color entries in the palette.

Reading the PCX Header

The PCX specification does not specifically state that the PCX image file format must use the least significant byte-ordering scheme used on Intel 80x 86 processors, but we may safely assume that this is so because the PCX format was developed for use on Intel-based machines. If code that reads PCX-format files will only be executed on Intel machines, it is possible, although not portable, to use the fread() function to read the header on a little-endian machine:

if(fread(&pcx, sizeof(char), sizeof(PCXHEADER), fp) !=
	fputs("Error reading PCX header.", stderr);

Compressing PCX Data

The data-encoding algorithm used in PCX files is a simple 1-byte/2-byte run-length encoding scheme. While this type of encoding is not the most effective in terms of reducing data size, it is very quick in its operation and quite easy to implement.

An image normally contains many series of pixel runs, that is, two or more contiguous pixels of the same value. Using the run-length data compression scheme, a run of pixels several bytes in length may be converted to a run code only two bytes in length.

The encoded data is read one byte at a time. If the two most significant bits (MSB) of the first byte read are set to 1, then this byte is the first byte of a 2-byte run code. The first byte in a 2-byte run code always contains the run count in its lower six bits, which is the length of the pixel run. Therefore, a pixel run may be 1 to 63 pixels in length.

Using the two most significant bits to indicate a 2-byte code rather than just one, MSB is a holdover from the early CGA days of Paintbrush. Use of only one MSB resulted in poor compression for CGA data, so two were used instead.

The second byte of a 2-byte run code is the value of the pixel run itself. This value may be in the range 0 to 255 and is written to the output a number of times equal to the run count.

If a run-count byte is read and the two MSBs are both 0, then this byte is a run-value byte, and the run count is considered to be 1. This 1-byte run code is used to prevent a 1-pixel run from encoding into a 2-byte run code.

The PCX RLE encoding scheme is not perfect, however. A 1-byte run code can contain a run value only in the range 0 to 63. If the pixel run value is in the range 64 to 255, a 2-byte run code must be used instead. If an image contains many single pixel runs of color values greater than 63, an increase of image data size can occur after PCX encoding. Such an increase in data size typically occurs only in very noisy or grainy images.

Decoding a PCX Format File

To decode a file in PCX format, you must read the header of the file and calculate the following data:

  • Width of image in pixels

  • Length of image in scan lines

  • Number of bytes needed to hold a decoded scan line

  • Number of padding bytes at the end of each scan line

Calculate the image width and height from the image dimension values as follows:

ImageWidth  = XEnd - XStart + 1; /* Width of image in pixels */
ImageHeight = YEnd - YStart + 1; /* Length of image in scan lines */

Calculating the number of bytes required to hold a decoded scan line is necessary if the decoded image data is to be stored in a buffer. It is also necessary to determine if the image data has been encoded across scan lines. The number of color planes multiplied by the number of bytes per line per plane yields this value:

ScanLineLength = NumBitPlanes * BytesPerLine;

The length of padding at the end of a scan line may be determined by calculating the number of pixels in an unencoded scan line and comparing this value with the pixel width of the displayed image:

LinePaddingSize = ((BytesPerLine * NumBitPlanes) *
				  (8 / BitsPerPixel)) - ((XEnd - XStart) + 1);

The decoding steps are the following:

  1. Read a byte.

  2. If the two MSBs are set to 1, then mask off the run count.

  3. Read next byte.

  4. Write the byte a number of times equal to the run count.

  5. Else, if the two MSBs are set to 0, then mask off the run value.

  6. Write the byte once.

  7. Repeat steps 1 through 6 until the buffer is full.

The code used to decode a scan line of information is as shown as follows:

** Decode a PCX scan line.
** In this example the size of Buffer[] and the value of BufferSize
** is equal to the scan line length. Data is read from the FILE
** stream fpIn and written to Buffer[].
  byte = GetByte(fpIn);                  /* Get next byte */
  if ((byte & 0xC0) == 0xC0)             /* 2-byte code */
	runcount = byte & 0x3F;              /* Get run count */
	runvalue = GetByte(fpIn);            /* Get pixel value */
  else                                   /* 1-byte code */
	runcount = 1;                        /* Run count is one */
	runvalue = byte;                     /* Pixel value */
  /* Write the pixel run to the buffer */
  for (total += runcount;                /* Update total */
	runcount && index < BufferSize;      /* Don't read past buffer */
  runcount--, index++)                   /* Update counters */
  Buffer[index] = runvalue;              /* Assign value to buffer */
  } while (index < BufferSize);          /* Read to end of buffer */

The PCX specification states that a decoding break should occur at the end of each scan line. This means that when a run of data is being encoded, and the end of the scan line is reached, the run should stop and not continue across to the next scan line, if it is possible to stop it.

Decoding can be complicated by PCX files that have been encoded ignoring this rule. Encoding across scan lines gains a few extra bytes of compression, but the process of decoding a single scan line is made much more difficult.

Encoding PCX Image Data

The scheme for encoding a scan line is fairly straightforward with only a few exceptions. Raw data is read one byte at a time. The only information needed is the number of bytes in a scan line. The following is the procedure for encoding image data using the PCX compression algorithm:

  1. Read a byte of pixel data, and store the value.

  2. Set counter to 1.

  3. Read the next byte, and check if it is the same as the stored value.

  4. If it is the same, increment the counter.

  5. If it is not the same and the count is greater than one, or the count is 63, or if the end of the scan line has been reached, then mask on the two MSBs, and output the count value.

  6. Output the data value.

  7. Repeat steps 1 though 6 until all scan lines have been read.

PCX Image Data Format

Once a scan line has been decoded, the format of the data it contains depends upon the BitsPerPixel and the NumBitPlanes values found in the header. Knowing the data format of a scan line is necessary so you can parse the pixel data from a scan line for display of the image or conversion of the image file from one format to another. All scan lines in a PCX file always have the same format.

Scan-line pixel data is stored in one of two ways--either pixel-oriented or plane-oriented. Pixel-oriented data is stored with all the pixel data (either real data or indexes into a color palette) in a contiguous line. Plane-oriented data unrolls the pixel data into its red, green, and blue components and groups them by color across the scan line.

Single-plane data is stored pixel by pixel in one long plane that runs the length of the scan line. The data in the scan line is not the actual image data itself but is instead a series of index values into either the EGA or VGA color palettes. The exception for single-plane data is the 1-bit monochrome image, where each bit in a scan line maps directly as a pixel value.

How much of the scan-line data a single pixel occupies is determined from the BitsPerPixel value. For example, with one bit per pixel, every byte of scan-line data contains eight pixel values. With eight bits per pixel, every byte of scan-line data contains one pixel value. Monochrome, CGA, and 256-color VGA images usually contain only a single plane per scan line.

Scan lines with three planes are uncommon, but they do exist. 24-bit PCX images are stored using three bytes per pixel spread over three planes. The 24-bit data values are the actual color values for the image, and no color palette is used. Paintbrush for Windows 2.0 uses a 3-plane/1-bit data format to store 8-color images, where each pixel value is an index into the EGA color palette.

Images with four planes are usually 16-color EGA images. In addition to the red, green, and blue planes, there is a fourth intensity color plane that is specific to the EGA display card. Scan-line data in 4-plane images contains index values into the EGA palette.

Related File Formats

Several other formats are direct spinoffs of the PCX file format. And in most cases they are just specialized versions of PCX.

PCC image file format

Earlier versions of PC Paintbrush had the capability of clipping and copying an area of a PCX image and saving it to a file using the Copy To... command. The resulting file was saved as a PCX format file with the extension .PCC, possibly to indicate that the image the file contained was a portion of another image. The current version of PC Paintbrush does not use the .PCC extension and uses the .PCX extension instead.

DCX image file format

The PCX file format is capable of storing only a single image per file. Applications that require two or more PCX image files to be identified as belonging to the same group often use a naming convention that will identify a collection of PCX files as being related to one another.

One such application is FAX software, where each facsimile page is stored as an individual image in a separate file. PCX became a popular format for PC-based FAX software, because facsimile pages saved in this format could be viewed using many popular paint and image display programs that supported PCX. However, storing each FAX page as a separate file can become quite cumbersome and also confusing, if each image has a cryptic filename.

In an effort to store PCX files in a manner more appropriate to facsimile applications, the DCX file format was created. The DCX format stores up to 1023 PCX images within a single DCX file. Each image in the DCX file is a complete PCX image file, including header and palette information. In applications, DCX files may contain all of the pages of a facsimile transmission, a series of images of the same subject, or all of the illustrations within a document. The DCX header follows:

typedef struct _DcxHeader
  DWORD Id;                      /* DCX Id number */
  DWORD PageTable[1024];         /* Image offsets */

Id is a 4-byte word used to identify the file. The value of this word is 3ADE68B1h (987,654,321 decimal).

PageTable is a table of 1024 4-byte word values. The values in this table are the offsets of each PCX image contained within the DCX file. The offset of each PCX image is measured from the beginning of the file (byte 0). The last entry of the page list is the terminator value and is always set to zero.

Typically, a DCX file contains an entire 4096-byte page list (1023 4-byte offset values followed by a 4-byte terminator value), even if most of the values in the list are zero. Some DCX file writers may try to save space by writing only the values of the offsets, followed by a 0 terminating word, but not the remaining part of the list. It is, therefore, important never to expect the page list to be a full 4096 bytes in length. DCX file readers should always read one value at a time and stop when a word value of zero is read. If the first offset value in the page list is 1004h (4100 decimal), then an entire 4096-byte page list is contained within the DCX file.

The DCX format is quite convenient and very easy to use; however, this format suffers from one major drawback. When a series of PCX files is concatenated into a DCX file, all the information within the PCX files is preserved, but the actual names of the PCX files are lost. No provision in the DCX format (or in the PCX format for that matter) exists for storing the MS-DOS filename of the PCX image files. Therefore, if the original PCX filenames are important to your application, you will have to devise some sort of name list that is maintained outside of the DCX file. Future revisions of the DCX format might correct this oversight (perhaps by appending a name list onto the end of the DCX file itself).

For Further Information

For further information about the PCX format, see the format specification.

The PCX format was created and is maintained by ZSoft Corporation. For additional information, contact ZSoft at:

ZSoft Corporation
Attn: Shannon Donovan
450 Franklin Road, Suite 100
Marietta, GA 30067
Voice: 770-428-0008
FAX: 770-427-1150
BBS: 770-427-1045
CompuServe: 76702,1207

ZSoft publishes the following technical reference manual describing the PCX format:

ZSoft Corporation, Technical Reference Manual, Revision 5, Marietta, GA, 1990.

PCX is a very popular format that has been described in many books and magazine articles. The following manual and magazine articles also document the format and use of PCX files:

Ashdown, Ian, "PCX Graphics," C Users Journal, vol. 9, no. 8, August 1991, pp. 89-96.

Azer, S., "Working with PCX Files," Microcornucopia, no. 42, July-August 1988, p. 42.

Luze, Marv, "Printing PCX Files," C Gazette, vol. 5, no. 2, Winter 1990-91, pp. 11-22.

Quirk, K., "Translating PCX Files," Dr. Dobb's Journal, vol. 14, no. 8, August 1989, pp. 30-36, 105-108.

This page is taken from the Encyclopedia of Graphics File Formats and is licensed by O'Reilly under the Creative Common/Attribution license.

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