Follow-Up on Sensor Use and JPEG Compression: Is there a standard algorithm for Jpeg compression? My question really is would my compressed Jpeg image from my camera be the same as...

gwong1 Loc: Tampa, FL

Is there a standard algorithm for Jpeg compression? My question really is would my compressed Jpeg image from my camera be the same as taking a RAW image and converting to Jpeg with a software program? I have searched and not found an answer. Thanks, Gary

ronwande Loc: Hendersonville NC

I believe the algorithm is standard BUT there are various levels or amounts of compression. Most cameras have several choices of quality. Similarly editing software has choices for compression amount. Photoshop has a quality setting of 1 to 10 (or is it 1 to 12). To get the image quality the same might require some experimenting with the compression amount in the editing software. The highest quality setting produces very little compression. 80% or so will reduce the file size very significantly with little damage to the image.

Of course re-editing and re-saving a JPG image will degrade it more and more.

amehta Loc: Boston

gwong1 wrote:

Is there a standard algorithm for Jpeg compression? My question really is would my compressed Jpeg image from my camera be the same as taking a RAW image and converting to Jpeg with a software program? I have searched and not found an answer. Thanks, Gary

There are standard algorithms, but there are quite a few options. I don't know if we can easily know exactly which settings the camera is using.

The jpeg from your camera also has the post processing which you set the camera to do (white balance, color adjustments, noise reduction, sharpening, ...), all the stuff you will do yourself before saving the jpeg in your software.

gwong1 Loc: Tampa, FL

Thanks

ronwande wrote:

I believe the algorithm is standard BUT there are ... (show quote)

gwong1 Loc: Tampa, FL

Thanks

amehta wrote:

There are standard algorithms, but there are quite a few options. I don't know if we can easily know exactly which settings the camera is using.

The jpeg from your camera also has the post processing which you set the camera to do (white balance, color adjustments, noise reduction, sharpening, ...), all the stuff you will do yourself before saving the jpeg in your software.

speters Loc: Grangeville/Idaho

gwong1 wrote:

Is there a standard algorithm for Jpeg compression? My question really is would my compressed Jpeg image from my camera be the same as taking a RAW image and converting to Jpeg with a software program? I have searched and not found an answer. Thanks, Gary

The Jpeg has been processed by your camera as it "sees/thinks" the picture should look like. The Raw is "un-processed", if you just converted as is to Jpeg, it still will be technical-speaking a "un-processed"file, sort of, as no visible changes have been made. But that's the beauty of Raw, there is no compression "whatsoever'. It contains all the information, so you can squeak every last bit of "quality" out of it.

amehta Loc: Boston

speters wrote:

The Jpeg has been processed by your camera as it "sees/thinks" the picture should look like. The Raw is "un-processed", if you just converted as is to Jpeg, it still will be technical-speaking a "un-processed"file, sort of, as no visible changes have been made. But that's the beauty of Raw, there is no compression "whatsoever'. It contains all the information, so you can squeak every last bit of "quality" out of it.

The jpeg has been processed by the camera as you tell it to. You can set the white balance, sharpness, color saturation, noise reduction, etc. At least in the higher end cameras. So it's not just doing whatever it wants. :-)

gwong1 Loc: Tampa, FL

Thank you. Gary

speters wrote:

The Jpeg has been processed by your camera as it "sees/thinks" the picture should look like. The Raw is "un-processed", if you just converted as is to Jpeg, it still will be technical-speaking a "un-processed"file, sort of, as no visible changes have been made. But that's the beauty of Raw, there is no compression "whatsoever'. It contains all the information, so you can squeak every last bit of "quality" out of it.

gwong1 Loc: Tampa, FL

Thank you. Gary

amehta wrote:

The jpeg has been processed by the camera as you tell it to. You can set the white balance, sharpness, color saturation, noise reduction, etc. At least in the higher end cameras. So it's not just doing whatever it wants. :-)

speters Loc: Grangeville/Idaho

amehta wrote:

The jpeg has been processed by the camera as you tell it to. You can set the white balance, sharpness, color saturation, noise reduction, etc. At least in the higher end cameras. So it's not just doing whatever it wants. :-)

It still leaves you with an image file that was done by the camera and not like the one you would get, if you had done that yourself (your vision of the image/processing).

amehta Loc: Boston

speters wrote:

amehta wrote:

The jpeg has been processed by the camera as you tell it to. You can set the white balance, sharpness, color saturation, noise reduction, etc. At least in the higher end cameras. So it's not just doing whatever it wants. :-)

It still leaves you with an image file that was done by the camera and not like the one you would get, if you had done that yourself (your vision of the image/processing).

It leaves me with an image file that was done by the camera and not the one done by Lightroom. At no point am I interested in touching every single pixel myself. So if I move a "sharpen" slider in LR, I'm not deciding exactly what the algorithm is doing.

Plus, the camera does it really well.