| [2] | 1 | /*
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| 2 | * jmorecfg.h
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| 3 | *
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| 4 | * Copyright (C) 1991-1997, Thomas G. Lane.
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| 5 | * This file is part of the Independent JPEG Group's software.
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| 6 | * For conditions of distribution and use, see the accompanying README file.
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| 7 | *
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| 8 | * This file contains additional configuration options that customize the
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| 9 | * JPEG software for special applications or support machine-dependent
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| 10 | * optimizations. Most users will not need to touch this file.
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| 11 | */
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| 12 |
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| 13 |
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| 14 | /*
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| 15 | * Define BITS_IN_JSAMPLE as either
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| 16 | * 8 for 8-bit sample values (the usual setting)
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| 17 | * 12 for 12-bit sample values
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| 18 | * Only 8 and 12 are legal data precisions for lossy JPEG according to the
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| 19 | * JPEG standard, and the IJG code does not support anything else!
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| 20 | * We do not support run-time selection of data precision, sorry.
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| 21 | */
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| 22 |
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| 23 | #define BITS_IN_JSAMPLE 8 /* use 8 or 12 */
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| 24 |
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| 25 |
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| 26 | /*
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| 27 | * Maximum number of components (color channels) allowed in JPEG image.
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| 28 | * To meet the letter of the JPEG spec, set this to 255. However, darn
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| 29 | * few applications need more than 4 channels (maybe 5 for CMYK + alpha
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| 30 | * mask). We recommend 10 as a reasonable compromise; use 4 if you are
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| 31 | * really short on memory. (Each allowed component costs a hundred or so
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| 32 | * bytes of storage, whether actually used in an image or not.)
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| 33 | */
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| 34 |
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| 35 | #define MAX_COMPONENTS 10 /* maximum number of image components */
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| 36 |
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| 37 |
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| 38 | /*
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| 39 | * Basic data types.
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| 40 | * You may need to change these if you have a machine with unusual data
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| 41 | * type sizes; for example, "char" not 8 bits, "short" not 16 bits,
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| 42 | * or "long" not 32 bits. We don't care whether "int" is 16 or 32 bits,
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| 43 | * but it had better be at least 16.
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| 44 | */
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| 45 |
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| 46 | /* Representation of a single sample (pixel element value).
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| 47 | * We frequently allocate large arrays of these, so it's important to keep
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| 48 | * them small. But if you have memory to burn and access to char or short
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| 49 | * arrays is very slow on your hardware, you might want to change these.
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| 50 | */
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| 51 |
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| 52 | #if BITS_IN_JSAMPLE == 8
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| 53 | /* JSAMPLE should be the smallest type that will hold the values 0..255.
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| 54 | * You can use a signed char by having GETJSAMPLE mask it with 0xFF.
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| 55 | */
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| 56 |
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| 57 | #ifdef HAVE_UNSIGNED_CHAR
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| 58 |
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| 59 | typedef unsigned char JSAMPLE;
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| 60 | #define GETJSAMPLE(value) ((int) (value))
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| 61 |
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| 62 | #else /* not HAVE_UNSIGNED_CHAR */
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| 63 |
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| 64 | typedef char JSAMPLE;
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| 65 | #ifdef CHAR_IS_UNSIGNED
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| 66 | #define GETJSAMPLE(value) ((int) (value))
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| 67 | #else
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| 68 | #define GETJSAMPLE(value) ((int) (value) & 0xFF)
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| 69 | #endif /* CHAR_IS_UNSIGNED */
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| 70 |
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| 71 | #endif /* HAVE_UNSIGNED_CHAR */
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| 72 |
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| 73 | #define MAXJSAMPLE 255
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| 74 | #define CENTERJSAMPLE 128
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| 75 |
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| 76 | #endif /* BITS_IN_JSAMPLE == 8 */
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| 77 |
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