What is more important for Image Quality? Pixels or Compression?

Hi Gus,

I'd look for extra storage space in the form of a couple of cheap USB drives (2 backups)... in the meantime, pixel count is probably more important than JPG compression.

Cheers

Brian

 

It's an interesting question really... and we have two opinions in two posters... so I suppose a good test is needed.

Cheers

Brian

 

if you are using aperture then i would look into using 'referenced' files.

Shoot in high res jpeg or raw, but store the files on an external disk not in the Aperture Library... which is the default. Aperture will create a jpeg preview - you can set the size of this in preferences. The Jpeg preview lives in your Aperture library and is with you even when the drive with the master files is unplugged. You cant make adjustments to these previews when the master file is offline. but you can view them

it is the best of both worlds... you have a best resolution image safely backed up on another drive, and an image as good as your screen resolution on your computer where ever you go

K

 

Gus, let me put it to you that one day you grab a once in a lifetime shot - and it's low pixel count and/or high compression. You might regret that!

In your situation what I would do is shoot max resolution, highest quality JPEGs in camera. Once downloaded, sort out anything really good and retain as a large file, then resize/compress the rest. That way you keep your options open and get the best of both worlds. Or you could simultaneously shoot raw plus low quality JPEG. That way you've got a high quality image if you shoot something special, otherwise just delete all the raw files from your computer and retain the JPEGs.

It seems a shame to pay a lot of money for a camera capable of high IQ then deliberately cripple it by taking low resolution shots. You can do that on a smaller, lighter and cheaper P&S! Just my opinion.....:smile:

 

It might actually be a combination of both. The reason is compression quality is not linear - as in the last 10% (90-100) is not as noticeable as say 10% at 40-50, but the file size difference at the last 10% is huge where it's negligible around the middle.

Here's an actual photo example to think about (using an e-p1)

large super fine image is at 99% jpeg quality : 6,592 kb
if I change the compression after to say 92% : 1,777 kb
at 86% : 1,208 kb

The reason I picked 92% is because I find that's my favourite compression level, it's where the image size ceases to drop drastically but the quality (for me) is un-noticeably worst. There's people who say 86% is not-noticeable but I can almost always see it's worst at that level, and if you notice the file size difference... it's not much, so I stay with 92%.

Here's pixel size examples :

large super fine 99% : 6,592 kb
2560x1920 99% : 2,354 kb
1600x1200 99% : 897kb

large 92% : 1,777 kb
2560x1920 92% : 748 kb
1600x1200 92% : 283 kb

So as you can see, changing the compression just to the 92% point makes a drastic difference in the file size, much more than scaling it down 1 ratio. I would personally take a 92% 2560x1920 image over a 1600x1200 99% image any day. I doubt many people would notice the quality difference between 99% and 92%.

Notice how much smaller the 1600x1200 at 92% is compared to everything else. I can't imagine you'd be looking for anything smaller than that.

Don't take my word for it though, test it out yourself. Your camera etc may have different sizes / compressions as mine. Take a picture, play with saving it as different compressions, and different sizes. I'd always advise on photo-ing it at full size and quality though - but that's just me.

P.S. my e-p1 usually uses 92% for "normal" mode, although I think I've seen it go lower on rare occasion.