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Resizing 6M->3M 'in camera'

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Barnaby Madgett

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On the 6900, is there a way to resample a 6M image down to 3M 'in camera', without any cropping? The reason I ask is that I'd like to be able to take all shots at 6M fine but then if the card gets filled up I could go through downsizing those shots I deem it's unlikely I'll want to print at large size, thus saving space but without having to actually delete them totally. Useful when on holiday with a limited number of cards available...

It's possible this is an easy thing to accomplish, but I've only had the camera since Monday so please bear with me :-)

Barns
 
Barnaby Madgett said:
On the 6900, is there a way to resample a 6M image down to 3M 'in
camera', without any cropping? The reason I ask is that I'd like to
be able to take all shots at 6M fine but then if the card gets
filled up I could go through downsizing those shots I deem it's
unlikely I'll want to print at large size, thus saving space but
without having to actually delete them totally. Useful when on
holiday with a limited number of cards available...

It's possible this is an easy thing to accomplish, but I've only
had the camera since Monday so please bear with me :-)

Barns
Click to expand...
Barns,

Many of who've had the camera for several months are on our 'N' th read-through of the manual - and speaking for myself, I still find new things on each re-read!

Meanwhile, have a look at pages 35-36 and see if this will help, although it specifically talks about trimming. Unfortunately I don't think the 6900 cam downsize in the way you suggest.
--Regards,Robin [Redbreast]
 
Redbreast [UK] said:
Barnaby Madgett said:
It's possible this is an easy thing to accomplish, but I've only
had the camera since Monday so please bear with me :-)

Barns
Click to expand...
Many of who've had the camera for several months are on our 'N' th
read-through of the manual - and speaking for myself, I still find
new things on each re-read!

Meanwhile, have a look at pages 35-36 and see if this will help,
although it specifically talks about trimming. Unfortunately I
don't think the 6900 cam downsize in the way you suggest.

--
Regards,

Robin [Redbreast]
Click to expand...
Hi barnes, yes trimming is what the 6900 offers but it is nearly as good as resising as it always converts the 6m picture to 3m if not more than 50% is trimmed. In practice we all take pictures that could do with atrim. If this is small one click on the trim function will only shave the edge off the picture AND reduce to a 3M pic. On hliday I do this all the time , even down to 1.3 meg for those not quite so important shots. Try it.--Richard Dunn
 
Richard Dunn said:
Hi barnes, yes trimming is what the 6900 offers but it is nearly as
good as resising as it always converts the 6m picture to 3m if not
more than 50% is trimmed. In practice we all take pictures that
could do with atrim. If this is small one click on the trim
function will only shave the edge off the picture AND reduce to a
3M pic. On hliday I do this all the time , even down to 1.3 meg for
those not quite so important shots. Try it.
--
Richard Dunn
Click to expand...
Hi both, thanks for the replies. Yes I'd just worked out actually that trimming even the smallest amount reduced down to 3M size - that's perfect for what I need - I'm a Happy Bunny :-)

Barns
 
Hmm, just been trying this out.

I took a picture at 6M fine - filesize 2.2Mb
Trimmed it '1 notch' in the camera, saved as 3M - filesize 555k (!)
Took the same picture with 3M fine straight off - filesize 1.2Mb

If I compare the 'trimmed' 3M picture vs the 'native' 3M picture, the native one is crisper and clearer. Is it possible that the trim function perhaps saves using 'normal' compression rather than fine? If so, is there any way to change this?

Barns
 
Barnaby Madgett said:
If I compare the 'trimmed' 3M picture vs the 'native' 3M picture,
the native one is crisper and clearer. Is it possible that the trim
function perhaps saves using 'normal' compression rather than fine?
Click to expand...
The camera might be recompressing the already compressed picture (something one should avoid), but I'm not sure about that. You can crop JPEGs without a lossy recompression -- or rather, clever software can -- so it doesn't have to be the case. But keep in mind that a "native" 3MP image is scaled down from the full 6MP as interpolated from the SuperCCD, thus two pixels from the 6MP image contribute to a single pixel in the 3MP image. Whereas when you crop (not scale) a 6MP image down to 3MP, you have a one-to-one correspondence between pixels. (If 3MP pictures from a given 3MP camera show more detail than 2MP pictures from a given 2MP camera, the pictures from the 3MP camera will still be superior, even when you shoot in 2MP mode.)
 
Michael J. Hußmann said:
Barnaby Madgett said:
If I compare the 'trimmed' 3M picture vs the 'native' 3M picture,
the native one is crisper and clearer. Is it possible that the trim
function perhaps saves using 'normal' compression rather than fine?
Click to expand...
The camera might be recompressing the already compressed picture
(something one should avoid), but I'm not sure about that. You can
crop JPEGs without a lossy recompression -- or rather, clever
software can -- so it doesn't have to be the case. But keep in mind
that a "native" 3MP image is scaled down from the full 6MP as
interpolated from the SuperCCD, thus two pixels from the 6MP image
contribute to a single pixel in the 3MP image. Whereas when you
crop (not scale) a 6MP image down to 3MP, you have a one-to-one
correspondence between pixels. (If 3MP pictures from a given 3MP
camera show more detail than 2MP pictures from a given 2MP camera,
the pictures from the 3MP camera will still be superior, even when
you shoot in 2MP mode.)
Click to expand...
Hmm yes I see your point, however the cropping I was doing wasn't cutting a 3M-pixel size from the 6M pixels, it was cutting (virtually) the whole 6M pixels (a single 'up' click on the zoom control), and the result was then saved at 3M quality by the camera, so there was some in-camera resampling going on - it had virtually all the 6M pixels there to generate the new 3M image from.

I'm starting to suspect that actually the quality loss is due to the fact that the two sequences went something like:

6M picture-> JPEGged-> resample down to 3M by trim-> JPEGged
vs
3M picture-> JPEGged

Therefore there are two sets of JPEG compression going on when I'm trimming vs a single JPEG compression when I take in 3M-fine straight off. I guess since JPEG is lossy then I'll 'lose' a bit of clarity each time. Perhaps to confirm this I could try instead doing :

6M-'Hi'-> resample to 3M by trim-> JPEGged

and see how this looks, since 'Hi' is lossless so I'd only have the single JPEG compression in the sequence. Doesn't help much though since Hi images are far too big for me to use in anger :-)

Cheers for your thoughts

Barns
 
Barnaby Madgett said:
Michael J. Hußmann said:
Barnaby Madgett said:
If I compare the 'trimmed' 3M picture vs the 'native' 3M picture,
the native one is crisper and clearer. Is it possible that the trim
function perhaps saves using 'normal' compression rather than fine?
Click to expand...
The camera might be recompressing the already compressed picture
(something one should avoid), but I'm not sure about that. You can
crop JPEGs without a lossy recompression -- or rather, clever
software can -- so it doesn't have to be the case. But keep in mind
that a "native" 3MP image is scaled down from the full 6MP as
interpolated from the SuperCCD, thus two pixels from the 6MP image
contribute to a single pixel in the 3MP image. Whereas when you
crop (not scale) a 6MP image down to 3MP, you have a one-to-one
correspondence between pixels. (If 3MP pictures from a given 3MP
camera show more detail than 2MP pictures from a given 2MP camera,
the pictures from the 3MP camera will still be superior, even when
you shoot in 2MP mode.)
Click to expand...
Hmm yes I see your point, however the cropping I was doing wasn't
cutting a 3M-pixel size from the 6M pixels, it was cutting
(virtually) the whole 6M pixels (a single 'up' click on the zoom
control), and the result was then saved at 3M quality by the
camera, so there was some in-camera resampling going on - it had
virtually all the 6M pixels there to generate the new 3M image from.

I'm starting to suspect that actually the quality loss is due to
the fact that the two sequences went something like:

6M picture-> JPEGged-> resample down to 3M by trim-> JPEGged
vs
3M picture-> JPEGged

Therefore there are two sets of JPEG compression going on when I'm
trimming vs a single JPEG compression when I take in 3M-fine
straight off. I guess since JPEG is lossy then I'll 'lose' a bit of
clarity each time. Perhaps to confirm this I could try instead
doing :

6M-'Hi'-> resample to 3M by trim-> JPEGged

and see how this looks, since 'Hi' is lossless so I'd only have the
single JPEG compression in the sequence. Doesn't help much though
since Hi images are far too big for me to use in anger :-)

Cheers for your thoughts

Barns
Click to expand...
Hi Barns,

I'd not really thought about quality loss and not spotted it before. But then I normally shoot with normal compression 6M. I went through my recent holiday photos and couldn't spot those that had been trimmed by the quality. Maybe it only matters with side by side comparisons but in real life may not be important.

Incidently sharpened images make bigger jpg files than soft images. However if a double jpg compreassion is going on there will be some detail loss.
Cheers--Richard Dunn
 
Barnaby Madgett said:
Therefore there are two sets of JPEG compression going on when I'm
trimming vs a single JPEG compression when I take in 3M-fine
straight off. I guess since JPEG is lossy then I'll 'lose' a bit of
clarity each time.
Click to expand...
It ain't necessarily so ... decompressing and recompressing would be the naive approach which Fuji may or may not have taken, but there's an alternative. JPEG deals with blocks of 8 x 8 pixels at a time, and these blocks are then compressed individually. As long as the width and height of the cropped image is still a multiple of 8, the already compressed JPEG data won't need to be recompressed; it's sufficient to discard the unnecessary blocks and keep the ones within the cropped image.
 
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