I have a PHP application where...
- User uploads a scanned image (png or jpg)
- I create annotations that are saved as a transparent png.
- Those annotations are "embedded" into the scans and the output is a png file.
All works well except if the images are PNG-8's. So, I don't know if this is possible, but could I convert a PNG-8 to a PNG-24 (or some other kind of PNG)?
I don't know much about PNG types, but according to http://www.fileformat.info, the metadata of a working image looks like this...
<javax_imageio_png_1.0>
<IHDR width="600" height="764" bitDepth="8" colorType="RGB" compressionMethod="deflate" filterMethod="adaptive" interlaceMethod="none"/>
<pHYs pixelsPerUnitXAxis="7874" pixelsPerUnitYAxis="7874" unitSpecifier="meter"/>
<tIME year="2013" month="4" day="25" hour="14" minute="9" second="17"/>
</javax_imageio_png_1.0>
And metadata from a failing image looks like this...
<javax_imageio_png_1.0>
<IHDR width="600" height="755" bitDepth="8" colorType="Grayscale" compressionMethod="deflate" filterMethod="adaptive" interlaceMethod="none"/>
<pHYs pixelsPerUnitXAxis="7874" pixelsPerUnitYAxis="7874" unitSpecifier="meter"/>
<tIME year="2013" month="4" day="23" hour="21" minute="10" second="33"/>
</javax_imageio_png_1.0>