Camera JPG file sizes?
Discussion
I used to use a Canon IXUS 400 - 4 Megapixel and at full res the JPG file sizes were about 2MB each (give or take quite a bit).
I now have a Nikon D70 which is 6 megapixel and the JPG file sizes are about 2.5 MB.
I also now have a Nikon Coolpix S1 which is 5 megapixel - and even at max res the JPG files sizes are only 1 MB - how come they are so small?
Is it simply that the Coolpix uses a high-compression/low-quality factor on the JPG and that the other cameras use a low-compression/high-quality setting - or is there somehting else hapenning here? Anyone know if I can make it use a higher-quality setting?
I now have a Nikon D70 which is 6 megapixel and the JPG file sizes are about 2.5 MB.
I also now have a Nikon Coolpix S1 which is 5 megapixel - and even at max res the JPG files sizes are only 1 MB - how come they are so small?
Is it simply that the Coolpix uses a high-compression/low-quality factor on the JPG and that the other cameras use a low-compression/high-quality setting - or is there somehting else hapenning here? Anyone know if I can make it use a higher-quality setting?
_dobbo_ said:
It will be a combination of the compression and the subject of the image.
Take a picture with the lens cap on and compare that to a picture of a complicated multi-coloured scene, you should see a very different file sizes.
The subjects of the pictures I'm comparing would not cause the file sizes to differ dramatically.
I'm talking about average/typical pictures sizes, not one-off exceptions.
dinkel said:
I'm not a fan of the compression as used by the D70 . . . Canon D350 and Olympus pics are a bit bigger but have way better quality. I wonder if you can fiddle a bit with Nikons compression. Use Raw if you want top quality
It's the Coolpix I'm questioning - I'm quite happy with the D70 - I was really complaining that the Coolpix seems to get too good a compression compared to other cameras - that scares me as I would assume it means quality further compromised.
Interesting isn't it.
I have a Pentax S5i (5 Mpix)and typically the top quality shots it offers give a file of a around 3Mb +/- 10%
My daughter has a Casio Exilim Z57 - also 5 Mpix and using the same lens as the Pentax. It would not surprise my if it was the same camera under the skin with a few cosmetic design changes and slightly different software. Typical file sizes for the same maximum picture resolution are 2 to 2.4 Mb.
Frankly when I checked the results side by side I could not tell the difference except the Casio gave a livelier colour balance and even seemed a little sharper sometimes. Of course it might well appear like that due to in camera sharpening on a higher compression. For all practical purposes with the type of camera and its limitations I don't think it would make any difference.
I also have a Canon Wireless iXUS (5 Mpix again) which seems to have an even wider range of file sizes to offer at max resolution. Multicolour outdoor in bright sunshine gives about 2.8Mb. Indoor, flash, and with lots of dark areas can be less then 1Mb. I have not yet tried a real back to back test but I suspect that it is compressing light and dark areas quite a lot and applying a fair amount of sharpening which will tend to reduce the image colour complexity where it is applied most. Or at least that's what it looks like it is doing.
Unless you are planning to print very large or crop a very small area and print that relatively large, I doubt you would really notice the difference. The ultimate resolution of the small lenses compared to the SLR lenses is a different matter of course. But when it no longer is will be the day when SLR's become few and very expensive. IMO.
I have a Pentax S5i (5 Mpix)and typically the top quality shots it offers give a file of a around 3Mb +/- 10%
My daughter has a Casio Exilim Z57 - also 5 Mpix and using the same lens as the Pentax. It would not surprise my if it was the same camera under the skin with a few cosmetic design changes and slightly different software. Typical file sizes for the same maximum picture resolution are 2 to 2.4 Mb.
Frankly when I checked the results side by side I could not tell the difference except the Casio gave a livelier colour balance and even seemed a little sharper sometimes. Of course it might well appear like that due to in camera sharpening on a higher compression. For all practical purposes with the type of camera and its limitations I don't think it would make any difference.
I also have a Canon Wireless iXUS (5 Mpix again) which seems to have an even wider range of file sizes to offer at max resolution. Multicolour outdoor in bright sunshine gives about 2.8Mb. Indoor, flash, and with lots of dark areas can be less then 1Mb. I have not yet tried a real back to back test but I suspect that it is compressing light and dark areas quite a lot and applying a fair amount of sharpening which will tend to reduce the image colour complexity where it is applied most. Or at least that's what it looks like it is doing.
Unless you are planning to print very large or crop a very small area and print that relatively large, I doubt you would really notice the difference. The ultimate resolution of the small lenses compared to the SLR lenses is a different matter of course. But when it no longer is will be the day when SLR's become few and very expensive. IMO.
After the previous post I was playing with the iXus long exposure to see what it does with available light night shots.
So, point it at the nightglow from a nearby city and, set the max 15 seconds and see what happens.
At 50 ISO it created a darkish image and a 1.22Mb file.
At 200 ISO a somewhat brighter image and the extra detail resulted in a 2.43 MB file thought the framing was very slightly different.
With exactly the same framing and set to 400 ISO the image was brighter again, as expected, and resulted in a 3.35 Mb file.
I didn't try 100 ISO at the time.
All of these are for the highest image size setting - 2592x1944 .
Other adjustments available - using sepia or B&W or enhanced colour modes, etc., would be expected to change the file size as well.
Just as an experiment I took a colour shot, B&W shot and tottally overexposed B&W shot of the same sunny and detailed scene.
Colour, a few samples with various special settings appled, gave a file size of around 3.3 Mb, +/- .1 Mb depending on the special settings.
B&W gave 2.85 Mb.
Totally overexposed, resulting in a completely 'white' image gave 0.1 Mb.
Not sure whether this helps at all but it does suggest that file size is not a very accurate proxy for resulting quality in practical terms under mormal conditions.
So, point it at the nightglow from a nearby city and, set the max 15 seconds and see what happens.
At 50 ISO it created a darkish image and a 1.22Mb file.
At 200 ISO a somewhat brighter image and the extra detail resulted in a 2.43 MB file thought the framing was very slightly different.
With exactly the same framing and set to 400 ISO the image was brighter again, as expected, and resulted in a 3.35 Mb file.
I didn't try 100 ISO at the time.
All of these are for the highest image size setting - 2592x1944 .
Other adjustments available - using sepia or B&W or enhanced colour modes, etc., would be expected to change the file size as well.
Just as an experiment I took a colour shot, B&W shot and tottally overexposed B&W shot of the same sunny and detailed scene.
Colour, a few samples with various special settings appled, gave a file size of around 3.3 Mb, +/- .1 Mb depending on the special settings.
B&W gave 2.85 Mb.
Totally overexposed, resulting in a completely 'white' image gave 0.1 Mb.
Not sure whether this helps at all but it does suggest that file size is not a very accurate proxy for resulting quality in practical terms under mormal conditions.
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