Resizing jpegs: the cost

[liekloo]

Hi everyone,

I'm trying to decide on a digital camera (my first one :)) and have in mind the Fuji Finepix E550, or else the Sony DSC-W1 or -P100.

The Fuji seems most fit for me, but I miss a 6 MP 'fine' jpeg setting (it offers 6 MP 'normal' or 12 MP 'fine').

I realize there are more important criteria to make a choice, but I find image quality important and I don't feel very comfortable that my jpegs will be only half the size of the fine jpegs made with most other camera's.

In the DCRP review (http://www.dcresource.com/reviews/fuji/finepix_e550-review/), the author suggests the following way to get a jpeg better than the 6 MP 'normal' one: Resize a 12MP 'fine' jpeg to 6MP.
(The catch is that the 12MP jpeg made by the camera is more than twice the size of the 6MP).

My concern is that this process (resizing a lossy picture) will induce extra loss: doesn't resizing imply decompressing/compressing, resulting in subsequent lossy compressions (one in the camera, one during resizing) and thus degradation? Or can resizing be done without decompression?

So which of these 2 factors should be more important? Do you think resizing the 12 MP fine jpeg is indeed a good way to get maximum quality @ 6MP? Thanks in advance. :)

[Norm in Fujino]

My concern is that this process (resizing a lossy picture) will induce extra loss:

Unfortunately, I don't anything about the specific characteristics of the Fuji sensor that makes it create a 12MP file, but based on the review, I'd take the easy way out--though it may appear easy only to me :confused: : save in RAW format and handle the files with a raw converter. You'll get the original 12MP file together with additional data that can be adjusted in post production. The review says, however, that the Fuji software only converts to TIFF. That's not a terrible hurdle, but you will have to then use a third program to convert from TIFF to JPG if you want the latter format. But there *are* RAW converters out there like the free Raw Shooter Essentials (RSE) that will convert directly from raw to jpeg.

On the other hand, I doubt that you will be displeased with the 6MP files produced with the Fine setting. If you're not planning on printing any larger than A4, that should be plenty of quality in normal situations.

[liekloo]

Thank you for your quick reply. :)
Can anyone confirm that resizing really implies decompressing the jpeg and recompressing again? (Just to be sure).

[Balrog]

The way JPEG works, yup. The file would be decompressed / resized / recompressed.

[haikai]

My concern is that this process (resizing a lossy picture) will induce extra loss: doesn't resizing imply decompressing/compressing, resulting in subsequent lossy compressions (one in the camera, one during resizing) and thus degradation? Or can resizing be done without decompression?

So which of these 2 factors should be more important? Do you think resizing the 12 MP fine jpeg is indeed a good way to get maximum quality @ 6MP? Thanks in advance. :)


in short, yes, i think resizing from 12 to 6 mp is probably the best way if you're trying to get the optimum 6 mp image. if you resize the image this does not necessarily mean you introduce more compression (that is, unless you save to jpeg again). resizing and compressing are two very different things. if you resized your 12 mp image to 6 mp and saved in a lossLESS format such as tiff, targa, psd, or the like, then you have only made the image smaller, but have not introduced any more compression in the form of image artifacts, color loss, etc. honestly, even if you resaved as jpeg, assuming you kept the quality of the jpeg compression very high (ie - very little compression), the loss in quality would probably be negligeable. you will probably have gained enough resolution from downsizing it from 12 mp to make it worth it. resaving jpegs is usually more of an issue if you're talking about handling very optimized images to begin with (like the kind you will often see online).

i'm wondering why you want to resize down to 6 mp at all... that's way larger than what you'd expect to show on the web, and if you're trying to print from this, why not just keep it at 12 mp? of course, this is just how it is as i understand it- anyone out there feel free to disagree :)

-hai

[gary_hendricks]

I've some comments about the Fuji E550:

1) The screen is practically unusable in bright sunlight. It washes out in the sun, images turn too bright and white and washout, you have to use the viewfinder to take your picture in many instances and then review it on the screen by switching to playback mode and cup your hand over the screen .

2) There is no autofocus lamp on the camera. Under low light the camera frequently cannot focus. In other words, you might have to turn on a light. However, indoor shots always come out better if you turn on more background lights.

3) The flash does not always work properly indoors - I am not sure why. The pictures sometimes have to be reshot because the flash did not fire. Sometimes I have to change my position for the flash to fire. However, when it does fire, the pictures look fine (and sharp).

[liekloo]

i'm wondering why you want to resize down to 6 mp at all (...) why not just keep it at 12 mp?
The review said 12 MP images were "noisy, soft, unappealing", and reported better results for 6 MP (6 MP direct or via resizing). However, now that you make me think about it, I suspect this finding should be taken with a grain of salt (maybe the author looked at the image at a large magnification factor, revealing the fact that this camera isn't true 12 MP but a 'scaled up' 6 MP). After all, 12 MP JPEGs are probably the best quality (see also other review below).

However 12 MP images imply in practice large JPEGs (5 MB, as if RAW) on a (already expensive) xD card... a con that could be added to Gary Hendricks' comments above ;)

@all: thanks for your quick help! :)

For those looking for other good reviews on this camera:
http://www.dpreview.com/reviews/fujifilme550/page12.asp (page5 is interesting as it addresses the 6 vs 12 MP).
http://www.digitalcamerainfo.com/content/Fuji-FinePix-E550-Digital-Camera-Review.htm

[Balrog]

On the whole I think Fuji's interpolated 'Super' CCDs aren't really worth it in terms of the tradeoff between larger file sizes and extra resolution .. the funky octagonal arrangement is nice, sure, but it can't produce detail that isn't there ... and the fact that they restrict your JPEG quality at lower (i.e. non-interpolated) resolutions just turns me off even more .. sure, it's a novel idea, but why force it down your customers' throats?

On the other hand, their increased dynamic range SuperCCDs are truly nice... good ISO performance in tiny sensors can't be beat, now if only they could develop some compelling camera bodies to go with the sensors...