Photo file size - why different? (1 Viewer)

[Wickham]

I took two photos today, both 1024 x 768 TIF and the original file size of both is 2319 KB.

I reduced the sizes for Birdforum.

One is 778 x 578 px, (449,684 square px) and is 58 KB as a jpg, taken as f 5.6 at 1/250.

The other is 703 x 566 px (397,898 square px) and is 121 KB as a jpg, taken as f5.0 at 1/400.

Why is the bigger jpg photo the smaller file size?

 

[alancairns]

I took two photos today, both 1024 x 768 TIF and the original file size of both is 2319 KB.

I reduced the sizes for Birdforum.

One is 778 x 578 px, (449,684 square px) and is 58 KB as a jpg, taken as f 5.6 at 1/250.

The other is 703 x 566 px (397,898 square px) and is 121 KB as a jpg, taken as f5.0 at 1/400.

Why is the bigger jpg photo the smaller file size?

It's he result of the jpeg compression algorithm. The eventual file size depends on such factors as the amount of detail in the picture.

Alan

 

[Roy C]

I took two photos today, both 1024 x 768 TIF and the original file size of both is 2319 KB.

I reduced the sizes for Birdforum.

One is 778 x 578 px, (449,684 square px) and is 58 KB as a jpg, taken as f 5.6 at 1/250.

The other is 703 x 566 px (397,898 square px) and is 121 KB as a jpg, taken as f5.0 at 1/400.

Why is the bigger jpg photo the smaller file size?

Were they both saved at the same jpg compression setting?

 

[Wickham]

Were they both saved at the same jpg compression setting?

They were saved within seconds of each other using Irfanview and I did not change any settings.

I just cropped the sizes and saved as jpg. There is a window in Irfanview which asks for quality setting (it's on 80% at present) but I didn't alter it.

The one that was larger but had the smaller jpg file size has an out of focus green background (the close up photo of the dragonfly) while the other was a max zoom photo of fox cubs and has in focus detailed surround.

 

[rezMole]

Don't worry about it. JPEGs always tend to save at differing sizes. If there's a lot of relatively flat colour in the image (such as blurred backgrounds), this takes less space to save. Hence flight shots with lots of blue sky tend to be a lot smaller than shots of birds in trees, where there is a lot of detail to record.