JPG Compression

JBurt

What would a PS 10 or 12 compression translate to as a percentage?

Is there a chart somewhere?

digismile

The scale used in programs like photoshop doesn't equate to a specific % compression. It simply is a scale to imply more or less agressive attempts to compress the file.


It totally depends on the number of different colors in the photo. You can prove this by taking any one of your photos and saving it at level 10 compression. Then make a single color layer that is the exact same size. Both are exactly the same number of pixels. But the single color layer should save down to just 40-50K. I looked for the same kind of info a long time ago and found out the answer was "it depends" ...

For me, it comes down to what level of compression can I live with and not see significant artifacts. For most photos, I think the general consensus is that a compression of 8 is virtually identical to 10 but a fraction the size.

JBurt

digismile wrote:

The scale used in programs like photoshop doesn't equate to a specific % compression. It simply is a scale to imply more or less agressive attempts to compress the file.


It totally depends on the number of different colors in the photo. You can prove this by taking any one of your photos and saving it at level 10 compression. Then make a single color layer that is the exact same size. Both are exactly the same number of pixels. But the single color layer should save down to just 40-50K. I looked for the same kind of info a long time ago and found out the answer was "it depends" ...

For me, it comes down to what level of compression can I live with and not see significant artifacts. For most photos, I think the general consensus is that a compression of 8 is virtually identical to 10 but a fraction the size.

Thanks for the info.
I use PSP X and it uses a percentage for the amount of compression. I was just trying to find a comparable. I guess I'll have to figure it out myself.

Netgarden

JBurt wrote:

Thanks for the info.
I use PSP X and it uses a percentage for the amount of compression. I was just trying to find a comparable. I guess I'll have to figure it out myself.

My friend and I compared compressions with PS and PSP, I using PSP. She claimed PS did a better job of it. What I found out was that PS compresses less, so the actual picture was a tad better/brighter. Had nothing to do with the program, really. Once PSP was reduced to around the same amount, [can't recall exactly] but PSP was in the 7 range and PS was around 3. I do it by hand now and just keep reducing it until I see a visable change. Generally around 4-6 range. But can get away with a little more reduction.

I am thinking that PS's 10 would not be the same as PSP's 10. One way to find out. Reduce the same pic in each program and check the bytes after. PS was a little higher in bytes [this was a year ago on an older PS]

JBurt

Netgarden wrote:

My friend and I compared compressions with PS and PSP, I using PSP. She claimed PS did a better job of it. What I found out was that PS compresses less, so the actual picture was a tad better/brighter. Had nothing to do with the program, really. Once PSP was reduced to around the same amount, [can't recall exactly] but PSP was in the 7 range and PS was around 3. I do it by hand now and just keep reducing it until I see a visable change. Generally around 4-6 range. But can get away with a little more reduction.

I am thinking that PS's 10 would not be the same as PSP's 10. One way to find out. Reduce the same pic in each program and check the bytes after. PS was a little higher in bytes [this was a year ago on an older PS]

Thanks for the info.

Sorry it took so long to respond. I've been away from my computer since Fri afternoon. (2 HS football games Fri. and a carshow Sat.)

I know with PS the larger the number the less compression and with PSP the smaller the number the less compression. When I get an extra Rountuit I'll use it to figure it out. Til then, I'll just stick with a 1% compression factor in PSP for the least amount of compression.