blp shabash 430x45

Welcome, Guest
Username: Password: Remember me
Discussions about cameras, lenses, accessories, and image-processing.
  • Page:
  • 1

TOPIC: Converting 16 bit to 8 bit.

Converting 16 bit to 8 bit. 8 months 2 weeks ago #1639

  • Peter Johnston
  • Peter Johnston's Avatar Topic Author
  • Offline
  • Premium Member
  • Premium Member
  • Posts: 85
  • Thank you received: 33
Hi Ian
Regarding your wonderful DPP and PSE workflow.
If I wanted a high resolution jpeg image, so no downsizing required. Do I still need to sharpen after converting from 16 bit to 8 bit?
Cheers
Peter.

Please Log in to join the conversation.

Converting 16 bit to 8 bit. 8 months 2 weeks ago #1640

  • Ian Wilson
  • Ian Wilson's Avatar
  • Offline
  • Elite Member
  • Elite Member
  • Posts: 207
  • Thank you received: 218
Hello Peter,
I am glad to learn that you find my notes useful.

The answer to your question is that you should not need to sharpen after converting from 16-bit TIFF to 8-bit TIFF, this change should not affect the sharpness of the image. Similarly, if you convert from 16 or 8-bit TIFF to JPEG of the highest quality, this will not affect the sharpness. In fact, if you try to sharpen the resulting JPEG you will need to save the JPEG again and this will cause extra un-necessary and undesirable compression and loss of image information. In fact, do not make any adjustments to the JPEG as re-saving it will cause some degradation in image quality.

Depending upon the use of the hi-res JPEG, you may want to adjust the sharpness of the 16 or 8-bit TIFF file before finally saving as a JPEG. I am thinking particularly about making large prints; it is sometimes beneficial to boost the sharpness of the TIFF to make up for the loss of sharpness resulting from the printing process. However, in general, unless you are familiar with the particular printer and its performance, you should not try to do this. If you have a request for a hi-res JPEG, for example one of your BLP images, you just need to take the TIFF and convert and save as a JPEG of the highest quality, no extra sharpening needed.

I hope this helps, best wishes,
Ian

Please Log in to join the conversation.

Last edit: by Ian Wilson.

Converting 16 bit to 8 bit. 8 months 2 weeks ago #1641

  • Peter Johnston
  • Peter Johnston's Avatar Topic Author
  • Offline
  • Premium Member
  • Premium Member
  • Posts: 85
  • Thank you received: 33
Hi Ian
Just to clarify.
If I required a high resolution jpeg image, I don't need to do step 5 of the PSE workflow, which is, both, downsize and remove Gaussian blur.
Would that be correct?

Please Log in to join the conversation.

Converting 16 bit to 8 bit. 8 months 2 weeks ago #1642

  • Peter Johnston
  • Peter Johnston's Avatar Topic Author
  • Offline
  • Premium Member
  • Premium Member
  • Posts: 85
  • Thank you received: 33
Also Ian
If that is the case. Why doesn't the image become softer when you go from 16 bit to 8 bit?
Cheers.

Please Log in to join the conversation.

Converting 16 bit to 8 bit. 8 months 2 weeks ago #1643

  • Ian Wilson
  • Ian Wilson's Avatar
  • Offline
  • Elite Member
  • Elite Member
  • Posts: 207
  • Thank you received: 218
That's correct Peter, for a hi-res JPEG you do not usually downsize and remove Gaussian blur. The exception might be if you wanted a hi-res JPEG that was a particular number of pixels wide or high. Then you would be resampling the image and it would usually benefit from some sharpening using 'remove Gaussian blur'. For example, let's say your hi-res image is 3962 x 2000 px and you want to make it 3840 pixels wide to display on a 4k monitor, then it would still be considered a hi-res image but because the original was resampled to make the width a bit smaller, there will be some blur introduced which should be removed to show the image at its best on the 4k monitor.

Regarding your second question, 'why doesn't the image become softer when going from 16-bit to 8-bit'. The answer is that this conversion is only reducing the number of bits per colour channel, it is not downsizing the number of pixels used to display the image. Going from 16 to 8-bits only changes the resolution of colour differences which does not affect the spatial resolution of the image and therefore does not change the sharpness.

I hope this helps, best wishes,
Ian

Please Log in to join the conversation.

Converting 16 bit to 8 bit. 8 months 2 weeks ago #1644

  • Peter Johnston
  • Peter Johnston's Avatar Topic Author
  • Offline
  • Premium Member
  • Premium Member
  • Posts: 85
  • Thank you received: 33
Those answers certainly do help. Simply and clear.
Thank you so much.
Cheers
Peter.

Please Log in to join the conversation.

  • Page:
  • 1

CONTACT US

The easiest way to contact us is by emailing us at This email address is being protected from spambots. You need JavaScript enabled to view it.

The Our People page, in the About Us section, contains email links to each of the committee members.