IQ of Panasonic 14-45 f3.5-5.6 vs. Panasonic 12-35 f2.8

Started 6 months ago | Questions thread
boxerman
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Re: IQ of Panasonic 14-45 f3.5-5.6 vs. Panasonic 12-35 f2.8
In reply to FrankParis, 6 months ago

I understand what you say (below), but this is precisely the reason for my question. Why does everyone say CA correction from RAW is easy, but if you shoot JPEG, you are out of luck? As you say, it's all pixels. (Although, I don't know enough about the internal codings for the various processing programs to be confident they REALLY have a common coding. I did not want to presume that, for example, RAW pixel coding looks generic inside the processing program. In my part of the world, internal codings vary a LOT for both images and other things, like text and arrays. The codings are optimized for the particular purposes of the particular program.)

FrankParis wrote:

boxerman wrote:

This, of course, is a constant refrain on this forum. My question is why can't JPEG be correct for CA? Certainly it could be converted to many other formats, and processed in them. Why am I completely stuck with CA from JPEGs? (I hope the answer is not something stupid like nobody has implemented the algorithm for anything but RAW. But, then, maybe that would give some of us hope.)

Once an image is read into memory from disk, regardless of the format on disk, image processing programs are ignorant of the format on disk. The computer only sees an array of pixels. But every time you save that array to disk, the algorithm to compress to JPEG degrades the image. So don't start with a lossy compression format like JPEG. Saving to JPEG should be the last step of PP, and the last step of PP should be sharpening. I always work with TIF (a lossless disk format) until I'm ready to sharpen. Then I save to JPEG. But anything worth keeping I save the raw file in case I later change my mind or want to do some further experimenting. I don't keep TIF images on my hard disk after I've got an image the way I want it for keeping.

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Frank Paris

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The BoxerMan

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