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Name
MiniImage
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Description
MiniImage shows how to use the image codecs and encode and decode
between various file formats. (GIF codecs are in a separate
sample).
Note that the sample is designed to work in Decode/Encode pairs. For
example you can choose a file to decode and save it as a .raw file and
click on the encode button and encode the .raw file back to jpeg or bmp.
This is because lots of information from the decode session is carried
over to the encoded session like the width and height of the image
which is not known by looking at the raw data. So if you click encode
without first decoding, it may not work properly. The Display button
decodes the image to BGR565. For all other decode formats, click decode
after selecting your color format. This saves the image as a .raw file.
The files need to be located on an SD Card.
General Steps for decoding Images:
1. CodecMgrCreateSession()
You can pass in the imageParamP width and height as needed, for example if
you need a 240x240 of a 320x320 image, you can pass it in, else the size
of the image is assumed. The rowbytes are also automatically calculated and
need not be passed in. If the CodecMgrCreateSession() succeeds, the
imageParamP will now contain the width and height and rowByte of the image
that's going to be used by the decoding session. Note that enlarging of an
image is not possible, for example if you pass 320x320 as input to
CreateSession() and the image is 240x240, it still remains 240x240.
2. CodecMgrEncodeDecode()
One or multiple calls to this function. Note if you allocate a big enough
buffer, this call is executed only once. The buffer size is usually
rowByte * height but this may take up too much dynamic heap space, so it is
advisable to use small buffers and loop like it is done in the sample.
To allocate large chunks use MemGluePtrNew().
3. CodecMgrDeleteSession()
Make sure you delete the session.
General Steps for encoding images:
1. CodecMgrCreateSession()
Both BMP and JPEG take different output parameters. The imageParamP should be
known beforehand since you're encoding raw data.
2. CodecMgrEncodeDecode()
The output is a file which you have already opened.
3. CodecMgrDeleteSession()
Make sure you delete a session.
Note that for Index Images, you need to fill in a separate structure that
needs to be passed to CodecMgrEncodeDecode. Please check the example.
And also note that the bitmap data for the Palm has a coordinate system that
is inverted when compared to windows bitmaps, so don't be surprised if your
encoded bitmap looks inverted on Windows.
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Builds With
CodeWarrior
Palm OS Developer Suite
gcc
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Devices
All Palm devices
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Requirements
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Libraries Used
Codec Plugin Manager
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How to Run
1. Launch the MiniImage application
2. Make sure the 'decode' button is selected
3. Make sure SD card is inserted, and go to the directory where the image
files are, and select an image file (.jpg)
4. Select 'display' to display picture
5. Select the Color Format
6. Select 'decode' to decode the picture to a raw format
7. Tap on the 'encode' button on top of the screen
8. Tap on the first blue folder to open an input file from SD card [the
raw file from step 6 can be used here]
9. After a file is selected and the main screen is displayed, select file
format to be JPEG. Also select the the Color Format
10. Tap on 'encode' to encode the raw image file back to JPEG
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Note
For formats like GRAY8, Index8, Index4, Index1 the input has to be the
same format. For example the input bmp should be Index8 to get a Index8
decoded data. You will get a "No Codec found" if you try to pass a 24bit
bmp and try to decode it to Index8.
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