Image quality

[bornagain]

Good Morning

I have been playing around with the image quality on my camera. The JPEG file size on “normal” is 2.5 to 3.00 Mb and on “fine” is 5.7 to 6.10. What is the reason for the different qualities and is there any practical reason for using fine all the time or should I stick to normal bearing in mind any storage limits?

Thanks
Phil

 

[simonkit]

Hi Phil,

If you want the best IQ from your camera you should always use the highest quality setting - the higher the setting the less the file is compressed and the more data is retained, hence the larger file size. For ultimate IQ RAW is normally recommended although it does involve more effort/time and isn't for everyone, the highest quality jpg setting can produce excellent results and involves little/no processing on you part.

Memory is very cheap these days compared to the initial costs of buying the camera/lens so I certainly wouldn't let this dictate the quality setting to use on your camera

Simon

 

[Russ77]

Good Morning

I have been playing around with the image quality on my camera. The JPEG file size on “normal” is 2.5 to 3.00 Mb and on “fine” is 5.7 to 6.10. What is the reason for the different qualities and is there any practical reason for using fine all the time or should I stick to normal bearing in mind any storage limits?

Thanks
Phil

JPEGs are compressed files, the less compression the more of the information that's captured is contained within the file/image, therefore the images *should* be better quality and/or give you more scope to manipulate them if required.

Not sure what camera you have or if there's the option to record RAW images?

RAW format will contain all available information for the given image, in a practical example, my 7D's RAW file size is 25MB but the top quality JPEG is only 10MB, therefore the camera has effectively dumped over half the data it initially held for the image.

As to whether you should shoot in the highest possible resolution possible..... It depends.....

Memory cards are pretty cheap now so there's no real reason to skimp on storage, however it will depend more on what you're going to be using the shots for.

If it's just pictures to put on facebook then you could get away with a smaller/lower quality image. If you think there's any chance that you might get a nice big canvas printed then you want to be shooting in the highest possible quality available.

It's easy to make an image smaller but it's pretty difficult make one bigger and retain IQ

 

[bornagain]

Thanks Simon and Russ

I have a D90 so yes will be able to shoot in RAW but a bit further down the line for me. I need to work on taking better photos at this stage. Will be looking to get an external hard disc at some point as my iMac is 500Gb so will continue for now to use fine setting.

 

[Russ77]

Thanks Simon and Russ

I have a D90 so yes will be able to shoot in RAW but a bit further down the line for me. I need to work on taking better photos at this stage. Will be looking to get an external hard disc at some point as my iMac is 500Gb so will continue for now to use fine setting.

To be honest, shooting in RAW will allow you to produce better images as it gives you a lot more scope to improve them if you didn't quite nail it with the camera

Obviously there's no substitute to getting everything right when you press the shutter, however RAW is more fogiving than JPEG

 

[lucyb]

To be honest, shooting in RAW will allow you to produce better images as it gives you a lot more scope to improve them if you didn't quite nail it with the camera

Obviously there's no substitute to getting everything right when you press the shutter, however RAW is more fogiving than JPEG

I second this. I'm a newbie too and have found that shooting in RAW lets me fix many errors. But more than that, it helps me see where I've gone wrong and what I could do in camera next time. For example, by setting the white balance in pp I can really see the effect different modes has on the finished photo.

It does take a bit more time to process them of course, but you can always shoot in RAW+JPEG

 

[HoppyUK]

Storage space is not a reason to only shoot JPEG these days. Memory is so cheap - 8gb card £20, 1tb external hard drive £70.

If your 500gb hard drive is overflowing, then that's almost certainly because it's full of rubbish. The best way to save space, and make finding the good stuff a heck of a lot easier, is to delete the obvious crap as soon as you've had a chance to review it.

BTW, sorry to be picky but JPEGs don't just 'dump' loads of data to achieve smaller file sizes. They (mainly) reduce files by mathematical compression, which is not the same thing at all. The number of pixels remains the same. For example, you can express one million as 1+1+1+1 a million times, or as 1x1m. One takes a lot of storage and the other one next to nothing, but the answer is the same.

 

[Andy_S]

To see the difference take a picture using the 'fine' setting and one using the 'low' (not sure exactly what it's called) setting. On the computer zoom in as much as you can and you should be able to see the difference in the finer detail.

 

[petersmart]

my 7D's RAW file size is 25MB but the top quality JPEG is only 10MB, therefore the camera has effectively dumped over half the data it initially held for the image.

That's odd since my Canon 1Ds II's RAW size is 17MB and my JPEG "L" (the highest quality) is usually about 12 MB but can go from about 9MB to over 14MB depending on the detail within.

.

 

[Deleted member 34016]

Once you shoot Raw- theres no going back

I see were almost Neighbours ( Im in Taunton)

Les

 

[Russ77]

That's odd since my Canon 1Ds II's RAW size is 17MB and my JPEG "L" (the highest quality) is usually about 12 MB but can go from about 9MB to over 14MB depending on the detail within.

.

I should have probably put "about" 25mb, that's the figure it puts for the filesize when choosing the format so is probably an absolute worst case scenario...... although I'm curious now and may have to experiment

 

[petersmart]

I should have probably put "about" 25mb, that's the figure it puts for the filesize when choosing the format so is probably an absolute worst case scenario...... although I'm curious now and may have to experiment

RAW is usually a fixed size but JPEGs alter depending on the detail contained within them and the amount of compression.

.

 

[redhed17]

RAW is usually a fixed size but JPEGs alter depending on the detail contained within them and the amount of compression.

.

Sorry, but No, :nono: a RAW file size changes with the amount of detail same as a Jpeg. At least it has for the 5 cameras I've had that shot/shoot RAW. :shrug:

 

[petersmart]

Sorry, but No, :nono: a RAW file size changes with the amount of detail same as a Jpeg. At least it has for the 5 cameras I've had that shot/shoot RAW. :shrug:

Definitely not a good day for me today - that's the second mistake I've made :bonk:

You ARE right - I was mixing up MP (mega pixels) and MB (Mega bits).

Back to the docs for another brain transplant.

Yet oddly enough when I convert them to TIFFs to edit them the filesize IS always the same - whether RAW or JPEGs.

Anyone want to tell me why?

Please make it simple though.

.

 

[Russ77]

I'm sure someone with a lot more technical knowledge will add/correct this but.......

Each pixel on the sensor captures exposure information, this is digital information and is essentially a string of 1s and 0s, each colour is made up by a different combination/length of 1s and 0s and then you also have information about exposure etc.

Bumping up the ISO will increase the sensitivity of the sensor which increases the amount of information that can be recorded.

Therefore, say at ISO100 green might be recorded like 1010111000111 but at ISO1600 it could be 101011100011101011100011 (this is a really simplified version of what I understand about sensors, pixels and the capture of information)

Each position represents 1 byte of information, hence why the number of bytes, or in this case megabytes varies from shot to shot.

 

[mastertrinity]

.

Yet oddly enough when I convert them to TIFFs to edit them the filesize IS always the same - whether RAW or JPEGs.

Anyone want to tell me why?

Please make it simple though.

.

It's because TIFF isn't related to the camera capture process it contains loads more information as it can retain both 8 bit and 16 bit data plus more confusing processes but it requires more mb so that you can use it to print, transfer, edit etc because RAW simply can't do that. hard to explain really but that's why TIFFs are higher mb than the original file

 

[roseway]

I don't know about other makes, but Nikon NEF files are generally compressed, so the file size can (and does) certainly change.

 

[redhed17]

I'm sure someone with a lot more technical knowledge will add/correct this but.......

Each pixel on the sensor captures exposure information, this is digital information and is essentially a string of 1s and 0s, each colour is made up by a different combination/length of 1s and 0s and then you also have information about exposure etc.

Bumping up the ISO will increase the sensitivity of the sensor which increases the amount of information that can be recorded.

Therefore, say at ISO100 green might be recorded like 1010111000111 but at ISO1600 it could be 101011100011101011100011 (this is a really simplified version of what I understand about sensors, pixels and the capture of information)

Each position represents 1 byte of information, hence why the number of bytes, or in this case megabytes varies from shot to shot.

No. but again, that is not correct. :nono:

The camera sensor is an analogue device and records a signal, which is amplified and then converted to a digital format. Each photosite signal is either on or off whether above or below a threshold, and so the 0 or 1 of the binary system.

Changing the ISO does not record any more data, it just amplifies what signal is recorded even more (if being raised). Generally the ISO is raised in low light situations, normally when you want to hand hold the camera and use a shutter speed you can you hand hold at.

If you were getting an exposure of say 1/15th sec @ f2.8 and ISO 100 in a low light situation, but wanted a higher shutter speed to handhold, you could raise the ISO to 200 and if the aperture and light stayed the same, the shutter speed would be raised to 1/30th sec. The same amount of light has been recorded even though the shutter speed has halved because the change in ISO has amplified what light it received to record the same amount of light. No more data has been recorded, and in theory the file sizes should be quite similar of the same scene. The more any signal is amplified, the more noise it generates, and this could change the file size as the random speckles increase, though that could be negligible.

That is how I understand it. Please put me right if I have got it wrong.

 

[Nawty]

It's also wrong to think of it as individual pixels, have a read of this:

http://en.wikipedia.org/wiki/Bayer_filter

And then, for fun, have a look at this, which is how most people imagine camera sensors work:

http://www.sigmaphoto.com/shop/sd1-dslr-sigma
http://en.wikipedia.org/wiki/Foveon_X3_sensor

 

[Russ77]

No. but again, that is not correct. :nono:

Was there any need for the telling off?

Did I say I was the unquestionable expert??

I offered for people to correct be but I don't expect anyone to go frickin' school teacher on me!!!

I'll bow to superior knowledge but not attitude

 

[Nawty]

Also, the key to understanding the difference between RAW and JPG isn't in understanding RAW, it's understanding JPG:

http://en.wikipedia.org/wiki/JPEG

 

[redhed17]

Was there any need for the telling off?

Did I say I was the unquestionable expert??

I offered for people to correct be but I don't expect anyone to go frickin' school teacher on me!!!

I'll bow to superior knowledge but not attitude

I'm sorry that you saw the emoticon as being told off, I saw it as saying no. I can see how it could be taken that way now. Again, I apologise. And I also apologise to petersmart too for using that emoticon earlier in the thread.

 

[Russ77]

I'm sorry that you saw the emoticon as being told off, I saw it as saying no. I can see how it could be taken that way now. Again, I apologise. And I also apologise to petersmart too for using that emoticon earlier in the thread.

Fair enough fella, probably a little OTT from me too , one of those days but that isn't your problem :shake:

 

[bornagain]

Thanks Les, Russ et al. I got the answer to my question and now understand just how much I have to learn!

All very interesting and I look forward to moving on in due course. Will no doubt be back with more questions in the future but thanks for now.

Phil

 

[petersmart]

The more any signal is amplified, the more noise it generates, and this could change the file size as the random speckles increase, though that could be negligible.

That is how I understand it. Please put me right if I have got it wrong.

In fact that last statement IS a bit wrong - high ISO files tend to be quite abit larger than low ISO files.

I remember that on my 350D which showed how many pics I could get on a CF card the number went down quite considerably when I changed from 100 ISO to 1600 ISO.

If I remember I could get at least 30-40% more pics at 100 ISO than at 1600 ISO.

.

 

[petersmart]

I'm sorry that you saw the emoticon as being told off, I saw it as saying no. I can see how it could be taken that way now. Again, I apologise. And I also apologise to petersmart too for using that emoticon earlier in the thread.

Think nothing of it - If that's the worst life threw at me I would consider myself an extremely lucky man

.

 

[redhed17]

I just taken the same picture of the light shade at different ISO values and the file size changed quite a bit more than I thought it would.

ISO 100 - 1,028 kb
ISO 400 - 1,416 kb
ISO 800 - 1,840 kb
ISO 1600 - 2,106 kb

I've never noticed any of my cameras 'shots remaining' number change when I alter the ISO setting. And just trying it with three cameras they didn't change. :shrug:

From the results above though, they should be changing.

 

[HoppyUK]

I just taken the same picture of the light shade at different ISO values and the file size changed quite a bit more than I thought it would.

ISO 100 - 1,028 kb
ISO 400 - 1,416 kb
ISO 800 - 1,840 kb
ISO 1600 - 2,106 kb

I've never noticed any of my cameras 'shots remaining' number change when I alter the ISO setting. And just trying it with three cameras they didn't change. :shrug:

From the results above though, they should be changing.

On my 5D2 they change. I have a nearly full card installed, camera set to Raw only, shots remaining reads:

41 shots remaining at ISO100
40 @ 200
39 @ 400
39 @ 800
37 @ 1600
36 @ 3200
33 @ 6400

At the same time, when set for JPEG Large only it changes from 180 @ ISO100 to 130 @ ISO 6400.

When set for both Raw and JPEG Large, it changes from 32 @ ISO100 to 25 @ ISO6400.

 

[HoppyUK]

Interesting article on Optimising Exposure and Exposue-To-The-Right technique, from LuminousLandscape.com relating to this stuff, here http://www.luminous-landscape.com/tutorials/optimizing_exposure.shtml

Here's a quote:

"A camera's sensor is an analogue device. When light hits a sensel (pixel) an analogue signal is generated. That signal is proportional to the amount of light received...
"This analogue voltage is then converted into digital format within the camera by an IC called an Analogue to Digital converter...
"This digital data is then either saved to a data card as a proprietary raw file, or converted inside the camera into a JPG file."

 

[StewartR]

On my 5D2 they change. I have a nearly full card installed, camera set to Raw only, shots remaining reads:

41 shots remaining at ISO100 ... 33 @ 6400

At the same time, when set for JPEG Large only it changes from 180 @ ISO100 to 130 @ ISO 6400.

When set for both Raw and JPEG Large, it changes from 32 @ ISO100 to 25 @ ISO6400.

That's what I'd expect, Richard. Your camera is assuming that RAW files are about 25% larger at ISO 6400 than they are at ISO 100, and it's assuming that JPG files are about 40% larger at ISO 6400 than at ISO 100. In both cases that's because the camera assumes that high-ISO images will be noisier than low-ISO images, and noise affects the lossy JPG compression more than it affects the lossless RAW compression.