PNGSUITE

----------------

        testset for PNG-(de)coders

        created by Willem van Schaik

------------------------------------

This is a collection of graphics images created to test the png applications

like viewers, converters and editors. All (as far as that is possible)

formats supported by the PNG standard are represented.

1.      INTRODUCTION

--------------------

1.1     PNG capabilities

------------------------

Supported color-types are:

        -   grayscale

        -   grayscale + alpha-channel

        -   color palettes

        -   rgb

        -   rgb + alpha-channel

Allowed bitdepths are depending on the color-type, but are in the range

of 1-bit (grayscale, which is b&w) upto 16-bits.

Special features are:

        -   interlacing (Adam-7)

        -   gamma-support

        -   transparency (a poor-man's alpha solution)

1.2     File naming

-------------------

Where possible, the testfiles are 32x32 bits icons. This results in a still

reasonable size of the suite even with a large number of tests. The name

of each test-file reflects thetype in the following way:

        g04i2c08.png

        || |||+---- bit-depth

        || ||+----- color-type (descriptive)

        || |+------ color-type (numerical)

        || +------- interlaced or non-interlaced

        |+--------- parameter of test (in this case gamma-value)

        +---------- test feature (in this case gamma)

1.3     PNG formats

-------------------

color-type:

        0g          -   grayscale

        2c          -   rgb color

        3p          -   paletted

        4a          -   grayscale + alpha channel

        6a          -   rgb color + alpha channel

bit-depth:

        01          -   with color-type 0, 3

        02          -   with color-type 0, 3

        04          -   with color-type 0, 3

        08          -   with color-type 0, 2, 3, 4, 6

        16          -   with color-type 0, 2, 4, 6

interlacing:

        n           -   non-interlaced

        i           -   interlaced

2.      THE TESTS

-----------------

2.1     Sizes

-------------

These tests are there to check if your software handles pictures well, with

picture sizes that are not a multiple of 8. This is particularly important

with Adam-7 type interlacing. In the same way these tests check if pictures

size 1x1 and similar are ok.

        s01         -   1x1 pixel picture

        s02         -   2x2 pixel picture

        s03         -   3x3 pixel picture

        s04         -   4x4 pixel picture

        s05         -   5x5 pixel picture

        s06         -   6x6 pixel picture

        s07         -   7x7 pixel picture

        s08         -   8x8 pixel picture

        s09         -   9x9 pixel picture

        s32         -   32x32 pixel picture

        s33         -   33x33 pixel picture

        s34         -   34x34 pixel picture

        s35         -   35x35 pixel picture

        s36         -   36x36 pixel picture

        s37         -   37x37 pixel picture

        s38         -   38x38 pixel picture

        s39         -   39x39 pixel picture

        s40         -   40x40 pixel picture

2.2     Background

------------------

When the PNG file contains a background chunck, this should be used for

pictures with alpha-channel or pictures with a transparency chunck. For

pictures without this background-chunk, but with alpha, this testset

assumes a black background.

For the images in this test, the left-side should be 100% the background

color, where moving to the right the color should gradually become the

image pattern.

        bga         -   alpha + no background

        bgw         -   alpha + white background

        bgg         -   alpha + gray background

        bgb         -   alpha + black background

        bgy         -   alpha + yellow background

2.3     Transparency

--------------------

Transparency should be used together with a background chunk. To test the

combination of the two the latter 4 tests are there. How to handle pictures

with transparancy, but without a background, opinions can differ. Here we

use black, but especially in the case of paletted images, the normal color

would maybe even be better.

        tp0         -   not transparent for reference

        tp1         -   transparent, but no background chunk

        tbw         -   transparent + white background

        tbg         -   transparent + gray background

        tbb         -   transparent + black background

        tby         -   transparent + yellow background

2.4     Gamma

-------------

To test if your viewer handles gamma-correction, 6 testfiles are available.

They contain corrected color-ramps and a corresponding gamma-chunk with the

file-gamma value. These are created in such a way that when the viewer does

the gamma correction right, all 6 should be displayed identical.

If they are different, probably the gamma correction is omitted. In that

case, have a look at the two right coloumns in the 6 pictures. The image

where those two look the same (when looked from far) reflects the gamma of

your system. However, because of the limited size of the image, you should

do more elaborate tests to determine your display gamma.

        g03         -   file-gamma = 0.35, for display with gamma = 2.8

        g04         -   file-gamma = 0.45, for display with gamma = 2.2 (PC)

        g05         -   file-gamma = 0.55, for display with gamma = 1.8 (Mac)

        g07         -   file-gamma = 0.70, for display with gamma = 1.4

        g10         -   file-gamma = 1.00, for display with gamma = 1.0 (NeXT)

        g25         -   file-gamma = 2.50, for display with gamma = 0.4

2.5     Filtering

-----------------

PNG uses file-filtering, for optimal compression. Normally the type is of

filtering is adjusted to the contents of the picture, but here each file

has the same picture, with a different filtering.

        f0          -   no filtering

        f1          -   sub filtering

        f2          -   up filtering

        f3          -   average filtering

        f4          -   paeth filtering

2.6     Additional palettes

---------------------------

Besides the normal use of paletted images, palette chunks can in combination

with true-color (and other) images also be used to select color lookup-tables

when the video system is of limited capabilities. The suggested palette chunk

is specially created for this purpose.

        pp          -   normal palette chunk

        ps          -   suggested palette chunk

2.7     Ancillary chunks (under construction)

------------------------

To test the correct decoding of ancillary chunks, these test-files contain

one or more examples of these chunkcs. Depending on the type of chunk, a

number of typical values are selected to test. Unluckily, the testset can

not contain all combinations, because that would be an endless set.

The significant bits are used in files with the next higher bit-depth. They

indicate howmany bits are valid.

        cs3         -   3 significant bits

        cs5         -   5 significant bits

        cs8         -   8 significant bits (reference)

        cs3         -   13 significant bits

For the physical pixel dimensions, the result of each decoding should be

a sqare picture. The first (cdf) image is an example of flat (horizontal)

pixels, where the pHYS chunk (x is 1 per unit, y = 4 per unit) must take

care of the correction. The second is just the other way round. The last

example uses the unit specifier, for 1000 pixels per meter. This should

result in a picture of 3.2 cm square.

        cdf         -   physical pixel dimensions, 8x32 flat pixels

        cdh         -   physical pixel dimensions, 32x8 high pixels

        cds         -   physical pixel dimensions, 8x8 square pixels

        cdu         -   physical pixel dimensions, with unit-specifier

        ccw         -   primary chromaticities and white point

        ch1         -   histogram 15 colors

        ch2         -   histogram 256 colors

        cm7         -   modification time, 01-jan-1970

        cm9         -   modification time, 31-dec-1999

        cm0         -   modification time, 01-jan-2000

In the textual chunk, a number of the standard, and some non-standard

text items are included.

        ct0         -   no textual data

        ct1         -   with textual data

        ctz         -   with compressed textual data

2.8     Chunk ordering (still under construction)

----------------------

These testfiles will test the obligatory ordering relations between various

chunk types (not yet) as well as the number of data chunks used for the image.

        oi1         -   mother image with 1 idat-chunk

        oi2         -   image with 2 idat-chunks

        oi4         -   image with 4 unequal sized idat-chunks

        oi9         -   all idat-chunks of length one

2.9     Compression level

-------------------------

Here you will find a set of images compressed by zlib, ranging from level 0 

for no compression at maximum speed upto level 9 for maximum compression.

        z00         -   zlib compression level 0 - none

        z03         -   zlib compression level 3

        z06         -   zlib compression level 6 - default

        z09         -   zlib compression level 9 - maximum

2.10     Corrupted files (under construction)

-----------------------

All these files are illegal. When decoding they should generate appropriate

error-messages.

        x00         -   empty IDAT chunk

        xcr         -   added cr bytes

        xlf         -   added lf bytes

        xc0         -   color type 0

        xc9         -   color type 9

        xd0         -   bit-depth 0

        xd3         -   bit-depth 3

        xd9         -   bit-depth 99

        xcs         -   incorrect IDAT checksum

3.      TEST FILES

------------------

For each of the tests listed above, one or more test-files are created. A

selection is made (for each test) for the color-type and bitdepth to be used

for the tests. Further for a number of tests, both a non-interlaced as well

as an interlaced version is available.

3.1     Basic format test files (non-interlaced)

------------------------------------------------

        basn0g01    -   black & white

        basn0g02    -   2 bit (4 level) grayscale

        basn0g04    -   4 bit (16 level) grayscale

        basn0g08    -   8 bit (256 level) grayscale

        basn0g16    -   16 bit (64k level) grayscale

        basn2c08    -   3x8 bits rgb color

        basn2c16    -   3x16 bits rgb color

        basn3p01    -   1 bit (2 color) paletted

        basn3p02    -   2 bit (4 color) paletted

        basn3p04    -   4 bit (16 color) paletted

        basn3p08    -   8 bit (256 color) paletted

        basn4a08    -   8 bit grayscale + 8 bit alpha-channel

        basn4a16    -   16 bit grayscale + 16 bit alpha-channel

        basn6a08    -   3x8 bits rgb color + 8 bit alpha-channel

        basn6a16    -   3x16 bits rgb color + 16 bit alpha-channel

3.2     Basic format test files (Adam-7 interlaced)

---------------------------------------------------

        basi0g01    -   black & white

        basi0g02    -   2 bit (4 level) grayscale

        basi0g04    -   4 bit (16 level) grayscale

        basi0g08    -   8 bit (256 level) grayscale

        basi0g16    -   16 bit (64k level) grayscale

        basi2c08    -   3x8 bits rgb color

        basi2c16    -   3x16 bits rgb color

        basi3p01    -   1 bit (2 color) paletted

        basi3p02    -   2 bit (4 color) paletted

        basi3p04    -   4 bit (16 color) paletted

        basi3p08    -   8 bit (256 color) paletted

        basi4a08    -   8 bit grayscale + 8 bit alpha-channel

        basi4a16    -   16 bit grayscale + 16 bit alpha-channel

        basi6a08    -   3x8 bits rgb color + 8 bit alpha-channel

        basi6a16    -   3x16 bits rgb color + 16 bit alpha-channel

3.3     Sizes test files

-----------------------

        s01n3p01    -   1x1 paletted file, no interlacing

        s02n3p01    -   2x2 paletted file, no interlacing

        s03n3p01    -   3x3 paletted file, no interlacing

        s04n3p01    -   4x4 paletted file, no interlacing

        s05n3p02    -   5x5 paletted file, no interlacing

        s06n3p02    -   6x6 paletted file, no interlacing

        s07n3p02    -   7x7 paletted file, no interlacing

        s08n3p02    -   8x8 paletted file, no interlacing

        s09n3p02    -   9x9 paletted file, no interlacing

        s32n3p04    -   32x32 paletted file, no interlacing

        s33n3p04    -   33x33 paletted file, no interlacing

        s34n3p04    -   34x34 paletted file, no interlacing

        s35n3p04    -   35x35 paletted file, no interlacing

        s36n3p04    -   36x36 paletted file, no interlacing

        s37n3p04    -   37x37 paletted file, no interlacing

        s38n3p04    -   38x38 paletted file, no interlacing

        s39n3p04    -   39x39 paletted file, no interlacing

        s40n3p04    -   40x40 paletted file, no interlacing

        s01i3p01    -   1x1 paletted file, interlaced

        s02i3p01    -   2x2 paletted file, interlaced

        s03i3p01    -   3x3 paletted file, interlaced

        s04i3p01    -   4x4 paletted file, interlaced

        s05i3p02    -   5x5 paletted file, interlaced

        s06i3p02    -   6x6 paletted file, interlaced

        s07i3p02    -   7x7 paletted file, interlaced

        s08i3p02    -   8x8 paletted file, interlaced

        s09i3p02    -   9x9 paletted file, interlaced

        s32i3p04    -   32x32 paletted file, interlaced

        s33i3p04    -   33x33 paletted file, interlaced

        s34i3p04    -   34x34 paletted file, interlaced

        s35i3p04    -   35x35 paletted file, interlaced

        s36i3p04    -   36x36 paletted file, interlaced

        s37i3p04    -   37x37 paletted file, interlaced

        s38i3p04    -   38x38 paletted file, interlaced

        s39i3p04    -   39x39 paletted file, interlaced

        s40i3p04    -   40x40 paletted file, interlaced

3.4     Background test files (with alpha)

------------------------------------------

        bgai4a08    -   8 bit grayscale, alpha, no background chunk, interlaced

        bgai4a16    -   16 bit grayscale, alpha, no background chunk, interlaced

        bgan6a08    -   3x8 bits rgb color, alpha, no background chunk

        bgan6a16    -   3x16 bits rgb color, alpha, no background chunk

        bgbn4a08    -   8 bit grayscale, alpha, black background chunk

        bggn4a16    -   16 bit grayscale, alpha, gray background chunk

        bgwn6a08    -   3x8 bits rgb color, alpha, white background chunk

        bgyn6a16    -   3x16 bits rgb color, alpha, yellow background chunk

3.5     Transparency (and background) test files

------------------------------------------------

        tp0n1g08    -   not transparent for reference (logo on gray)

        tbbn1g04    -   transparent, black background chunk

        tbwn1g16    -   transparent, white background chunk

        tp0n2c08    -   not transparent for reference (logo on gray)

        tbrn2c08    -   transparent, red background chunk

        tbgn2c16    -   transparent, green background chunk

        tbbn2c16    -   transparent, blue background chunk

        tp0n3p08    -   not transparent for reference (logo on gray)

        tp1n3p08    -   transparent, but no background chunk

        tbbn3p08    -   transparent, black background chunk

        tbgn3p08    -   transparent, light-gray background chunk

        tbwn3p08    -   transparent, white background chunk

        tbyn3p08    -   transparent, yellow background chunk

3.6     Gamma test files

------------------------

        g03n0g16    -   grayscale, file-gamma = 0.35

        g04n0g16    -   grayscale, file-gamma = 0.45

        g05n0g16    -   grayscale, file-gamma = 0.55

        g07n0g16    -   grayscale, file-gamma = 0.70

        g10n0g16    -   grayscale, file-gamma = 1.00

        g25n0g16    -   grayscale, file-gamma = 2.50

        g03n2c08    -   color, file-gamma = 0.35

        g04n2c08    -   color, file-gamma = 0.45

        g05n2c08    -   color, file-gamma = 0.55

        g07n2c08    -   color, file-gamma = 0.70

        g10n2c08    -   color, file-gamma = 1.00

        g25n2c08    -   color, file-gamma = 2.50

        g03n3p04    -   paletted, file-gamma = 0.35

        g04n3p04    -   paletted, file-gamma = 0.45

        g05n3p04    -   paletted, file-gamma = 0.55

        g07n3p04    -   paletted, file-gamma = 0.70

        g10n3p04    -   paletted, file-gamma = 1.00

        g25n3p04    -   paletted, file-gamma = 2.50

3.7     Filtering test files

----------------------------

        f00n0g08    -   grayscale, no interlacing, filter-type 0

        f01n0g08    -   grayscale, no interlacing, filter-type 1

        f02n0g08    -   grayscale, no interlacing, filter-type 2

        f03n0g08    -   grayscale, no interlacing, filter-type 3

        f04n0g08    -   grayscale, no interlacing, filter-type 4

        f00n2c08    -   color, no interlacing, filter-type 0

        f01n2c08    -   color, no interlacing, filter-type 1

        f02n2c08    -   color, no interlacing, filter-type 2

        f03n2c08    -   color, no interlacing, filter-type 3

        f04n2c08    -   color, no interlacing, filter-type 4

3.8     Additional palette chunk test files

-------------------------------------------

        pp0n2c16    -   six-cube palette-chunk in true-color image

        pp0n6a08    -   six-cube palette-chunk in true-color+alpha image

        ps1n0g08    -   six-cube suggested palette (1 byte) in grayscale image

        ps1n2c16    -   six-cube suggested palette (1 byte) in true-color image

        ps2n0g08    -   six-cube suggested palette (2 bytes) in grayscale image

        ps2n2c16    -   six-cube suggested palette (2 bytes) in true-color image

3.9     Ancillary chunks test files

-----------------------------------

        cs5n2c08    -   color, 5 significant bits

        cs8n2c08    -   color, 8 significant bits (reference)

        cs3n2c16    -   color, 13 significant bits

        cs3n3p08    -   paletted, 3 significant bits

        cs5n3p08    -   paletted, 5 significant bits

        cs8n3p08    -   paletted, 8 significant bits (reference)

        cdfn2c08    -   physical pixel dimensions, 8x32 flat pixels

        cdhn2c08    -   physical pixel dimensions, 32x8 high pixels

        cdsn2c08    -   physical pixel dimensions, 8x8 square pixels

        cdun2c08    -   physical pixel dimensions, 1000 pixels per 1 meter

        ccwn2c08    -   chroma chunk w:0.3127,0.3290 r:0.64,0.33 g:0.30,0.60 b:0.15,0.06

        ccwn3p08    -   chroma chunk w:0.3127,0.3290 r:0.64,0.33 g:0.30,0.60 b:0.15,0.06

        ch1n3p04    -   histogram 15 colors

        ch2n3p08    -   histogram 256 colors

        cm7n0g04    -   modification time, 01-jan-1970 00:00:00

        cm9n0g04    -   modification time, 31-dec-1999 23:59:59

        cm0n0g04    -   modification time, 01-jan-2000 12:34:56

        ct0n0g04    -   no textual data

        ct1n0g04    -   with textual data

        ctzn0g04    -   with compressed textual data

3.10    Chunk ordering

----------------------

        oi1n0g16    -   grayscale mother image with 1 idat-chunk

        oi2n0g16    -   grayscale image with 2 idat-chunks

        oi4n0g16    -   grayscale image with 4 unequal sized idat-chunks

        oi9n0g16    -   grayscale image with all idat-chunks length one

        oi1n2c16    -   color mother image with 1 idat-chunk

        oi2n2c16    -   color image with 2 idat-chunks

        oi4n2c16    -   color image with 4 unequal sized idat-chunks

        oi9n2c16    -   color image with all idat-chunks length one

3.11    Compression level

-------------------------

        z00n2c08    -   color, no interlacing, compression level 0 (none)

        z03n2c08    -   color, no interlacing, compression level 3

        z06n2c08    -   color, no interlacing, compression level 6 (default)

        z09n2c08    -   color, no interlacing, compression level 9 (maximum)

3.12     Currupted files

-----------------------

        x00n0g01    -   empty 0x0 grayscale file

        xcrn0g04    -   added cr bytes

        xlfn0g04    -   added lf bytes

        xc0n0c08    -   color type 0

        xc9n0c08    -   color type 9

        xd0n2c00    -   bit-depth 0

        xd3n2c03    -   bit-depth 3

        xd9n2c99    -   bit-depth 99

        xcsn2c08    -   incorrect IDAT checksum

--------

    (c) Willem van Schaik

        willem@schaik.com

        Singapore, October 1996