Recently, I wanted to convert a TIFF image taken from Apple’s Media site to the JPEG format. To do so, I opened the file in Preview and selected “Save As…” JPEG.
It did not go well. The colours in the resulting JPEG were inverted (much like a film negative, for those of you who can still recall this ancient artefact). Figuring I was not the first person to fall victim to this bug, I searched Apple’s Knowledge Base for help. Sure enough, I found an article confirming the symptom.
While the support article implies that the problem is restricted to Mac OS X 10.4 and 10.5, I can confirm that the bug is still alive and well in Mac OS X 10.6.4.
I found a further complication with Apple’s suggested work-around. The company advises you to select the “Generic RGB” profile from the Tools -> Match to Profile… command. After doing so, the TIFF-to-JPEG conversion should work. However, the Tools -> Assign Profile… command (as it is now called in the latest version of Preview) lists no RGB profile for TIFF images (at least it didn’t for the image I was using). I tried a few of the profiles that were listed; none of them squashed the inverted colour bug.
Not to worry. There are several other easy workarounds. One is to use a graphics program that can convert TIFF to JPEG (such as Photoshop Elements). Another is to use a screen capture program (such as Snapz Pro) to capture the image as a JPEG – so long as the image isn’t larger than your Mac’s screen resolution. Finally, you can even use Preview. To do so, select Print and save the document as a PDF. You can now open the PDF in Preview and save it as a JPEG. In all cases, there will be no unwanted colour inversion. The resulting images may not be a perfect colour match to the original. But they were certainly good enough for my intended use of posting the image to the web.