Originally posted by twitch Any image on screen is a jpeg conversion of your RAW file.
Not really. The image on the screen is a bit-mapped raster interpretation of the data stored in the original file. This is true regardless of format with the possible exception of the native bit-map format supported by the OS (e.g. Windows .bmp). When a RAW converter such as Lightroom (essentially Adobe Camera RAW) displays a RAW file, it does a temporary interpretation of the capture data into the graphics memory based on default development settings. When your browser displays a JPEG image, the contents are also rendered into the graphics memory, but in a manner specific to the JPEG format with all information required for display encoded in the file itself.
For Pentax the RAW rendering is (or should be) either a full 14-bit or 12-bit image depending on camera.
JPEG is always 8-bit (256 color shades maximum per channel R/G/B) regardless of the color depth of the original capture. An interpretation of the RAW data into JPEG almost always involves a munging of color values to fit the 8-bit limitation with significant opportunities for artifact and/or color shift. This can be demonstrated by doing a screen capture of both the displayed RAW data and that from an exported JPEG of the same image. A comparison of full-resolution crops from both is usually quite telling. They are not the same.
You are correct, however in laying the blame on the RAW converter if it does intermediate processing that results in display artifact. I suspect this is what is being done by Fastone. That is why I suggested making the DNG available for download so we could take a look-see at the unprocessed file in the RAW converter of choice.
As for color space conversion issues, I don't know that it would cause the problems present in the original post. Conventional wisdom is to capture and edit using a wide gamut and eventually down-sample to sRGB if screen display is the target to allow for consistent display across devices.
Steve