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File Size Question
Nov 17, 2019 11:46:36 #
lorvey wrote:
BigDaddy, thank you for responding. So, I am taking from this that the first image, the darker of the two, has more color variation, more detail, so it was not possible to compress the file as much as the second image. The second image must have more common color bits or pixels which makes it possible to compress further. This is probably an over simplification of what it is doing, but I am trying to understand this in layman's terms.
BigDaddy, thank you for responding. So, I am taking from this that the first image, the darker of the two, has more color variation, more detail, so it was not possible to compress the file as much as the second image. The second image must have more common color bits or pixels which makes it possible to compress further. This is probably an over simplification of what it is doing, but I am trying to understand this in layman's terms.
That would be my take on it. Jpeg compression is a complex subject few people on earth understand. Fortunately, a layman's understanding is pretty much all that's needed for you and me, or any photographer.
A long time ago I took a picture with my lens cap on, one in raw, one in jpeg. I figured the jpg only had one color to encode, so the file should have been really, really small compared to the raw file... I don't recall the outcome, and no longer am all that curious, but I don't think the jpg was as small as I expected, or I would remember more about it. I've planned on doing it again for at least 10 years, but never get a round toit. You might give it a shot and see what happens.... let me know.
Nov 17, 2019 14:12:58 #
lorvey wrote:
The pixel dimensions on these two photos is identical (3000 X 4000}. Both images were taken with my iPhone 7, so these are straight from the "camera". The file size of the first image is 5.3MB and the second one is 1.8MB. For the technical experts out there, I'm just curious, why is the file size so different? Must have something to do with black pixels vs white pixels?
Yes black pixels take up more space than white pixels. Always try to shoot high key to get the smallest file size.
Ok THAT IS A JOKE. I hope you are laughing.
The answer to the question has been provided in prior posts.
Nov 17, 2019 15:04:36 #
lorvey wrote:
The pixel dimensions on these two photos is identical (3000 X 4000}. Both images were taken with my iPhone 7, so these are straight from the "camera". The file size of the first image is 5.3MB and the second one is 1.8MB. For the technical experts out there, I'm just curious, why is the file size so different? Must have something to do with black pixels vs white pixels?
It's all about JPEG compression and the complexity of the image. The more tones the JPEG algorithm can represent with a bit of math, the smaller the file size.
Converted to bitmaps such as uncompressed TIFFs, both files would take up the same space on your drive.
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Nov 17, 2019 22:40:02 #
A very, very simple explanation, as I understand it. Consider a row of 100 varying shades of gray pixels in an image. Tiff compression applies the same amount of memory to each pixel regardless of the color. JPEG compression will compare side-by-side pixels. If ten gray pixels in a row are the same the first of the ten pixels is saved to memory but the following nine are only referenced to the first pixel. If the jpg image is saved with different software it may consider only 7 of the 10 mentioned gray pixels are the same and by doing so the size of the saved image will change. I know it's way more complex than this.
Nov 18, 2019 10:34:30 #
jwohlhueter wrote:
A very, very simple explanation, as I understand i... (show quote)
Makes sense. It's all about the JPG compression. Thank you for your reply.
Nov 18, 2019 10:35:42 #
burkphoto wrote:
It's all about JPEG compression and the complexity of the image. The more tones the JPEG algorithm can represent with a bit of math, the smaller the file size.
Converted to bitmaps such as uncompressed TIFFs, both files would take up the same space on your drive.
Converted to bitmaps such as uncompressed TIFFs, both files would take up the same space on your drive.
Thank you. Makes sense to me.
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