Save for Web Frustration

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I am using PS 7 on a Mac. I have some JPEG images (800 pixel maximum dimension) that I need to reduce to a maximum size of 75 KB for posting on a web site. So I open an image, display using 2-Up, and use the Optimize to File Size feature. To be safe I set the Desired File Size to 74 K. (In case it matters, for Start With I have Current Settings checked and for Use I have Current Slice checked). So it does its thing and decides to use Quality 38. At the bottom of the image on the right hand side it says 73.09 K. All well and good until after I save it and look in the folder the file is 76 K in size. This is confirmed by Get Info.

I sympathize, and think the web site people should lighten up on that requisite. 76 is close enough.

Here is why. Photoshop’s reading of the file size does not, or cannot factor in what is called a ‘cluster factor’ of the hard drive. In lay terms, cluster size is the ‘chunks’ allocated to a file’s storage. The larger the disc, the larger the cluster size. Every file is given ‘n’ amount of space, rounded UP to the next step (cluster size).

So your file on a tiny 20mb disk of the old days would be 73k. It gains an extra, slop factor on the big drives.

All you can do is lower the quality further.

Thanks. I set Optimize to File Size to 70 KB and that did the trick for all the files.

Another question, please. I would like to create an action to do this. If I record an action it stores the operations as an item called Export. Within Export, it says Quality 28, which I guess was the specific quality needed for the image that I used to create the action. It does say With Optimized, but there is no 70 KB listed anywhere. I also notice that each time I manually did the steps to Save for Web, I had to open the Optimize to File Size window, which by default had the 70 KB size loaded, but and hit okay before it optimized for 70 KB.

Thanks again.

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Thanks. I set Optimize to File Size to 70 KB and that did the trick for all the files.

Another question, please.

Unfortunately I do not have PS version 7, so I cannot answer.

<jjs> wrote:

wrote in message

I am using PS 7 on a Mac. I have some JPEG images (800 pixel maximum dimension) that I need to reduce to a maximum size of 75 KB for posting on a web site. So I open an image, display using 2-Up, and use the Optimize to File Size feature. To be safe I set the Desired File Size to 74 K. (In case it matters, for Start With I have Current Settings checked and for Use I have Current Slice checked). So it does its thing and decides to use Quality 38. At the bottom of the image on the right hand side it says 73.09 K. All well and good until after I save it and look in the folder the file is 76 K in size. This is confirmed by Get Info.

I sympathize, and think the web site people should lighten up on that requisite. 76 is close enough.

Here is why. Photoshop’s reading of the file size does not, or cannot factor in what is called a ‘cluster factor’ of the hard drive. In lay terms, cluster size is the ‘chunks’ allocated to a file’s storage. The larger the disc, the larger the cluster size. Every file is given ‘n’ amount of space, rounded UP to the next step (cluster size).

So your file on a tiny 20mb disk of the old days would be 73k. It gains an extra, slop factor on the big drives.

All you can do is lower the quality further.

There is no need to do that. Even if the file takes a little more space on a certain hard disk, that doesn’t mean it has really grown in size. Look at the size in bytes, not at that ‘XXX KB on Disk’ in front of it. If the file was smaller than 75 KB, it will still be smaller than 75 KB when you upload it, even if it takes 76 KB on *your* disk because of those blocks.

—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.com

On Feb 3, 6:44 am, (Johan W. Elzenga) wrote:

There is no need to do that. Even if the file takes a little more space on a certain hard disk, that doesn’t mean it has really grown in size. Look at the size in bytes, not at that ‘XXX KB on Disk’ in front of it. If the file was smaller than 75 KB, it will still be smaller than 75 KB when you upload it, even if it takes 76 KB on *your* disk because of those blocks.

Thanks for your reply, but how do you look at the size in bytes other than to see it’s file size in the Finder window or use Get Info which appears to give the same size? Also, since I am trying to meet a web sites maximum image size requirement, wouldn’t that site also see the "XXX KB on Disk" size and use that to determine whether to apply further compression, which is what I am trying to avoid?

wrote:

On Feb 3, 6:44 am, (Johan W. Elzenga) wrote:

There is no need to do that. Even if the file takes a little more space on a certain hard disk, that doesn’t mean it has really grown in size. Look at the size in bytes, not at that ‘XXX KB on Disk’ in front of it. If the file was smaller than 75 KB, it will still be smaller than 75 KB when you upload it, even if it takes 76 KB on *your* disk because of those blocks.

Thanks for your reply, but how do you look at the size in bytes other than to see it’s file size in the Finder window or use Get Info which appears to give the same size? Also, since I am trying to meet a web sites maximum image size requirement, wouldn’t that site also see the "XXX KB on Disk" size and use that to determine whether to apply further compression, which is what I am trying to avoid?

If you use ‘Get Info’, you will see the size on disk and then the true file size in bytes. The latter is what counts, not the first. What that remote site sees depends on how the upload process works, but usually it will see the file as it is sent, so the true size. If not, your file will probably be rejected because it is too large, so it’s simply a matter of trying.

—
Johan W. Elzenga johan<<at>>johanfoto.nl Editor / Photographer http://www.johanfoto.com

In article
,
"" wrote:

To be safe I set the Desired File
Size to 74 K. (In case it matters, for Start With I have Current Settings checked and for Use I have Current Slice checked). So it does its thing and decides to use Quality 38. At the bottom of the image on the right hand side it says 73.09 K. All well and good until after I save it and look in the folder the file is 76 K in size. This is confirmed by Get Info.

Correct. To understand what is happening, you must first understand how hard disks work.

When you save a file on a hard disk, the file takes up more space on the disk than its size would make you think. Space on a hard disk is allocated in chunks. In Mac OS X, the size of a chunk is 4 K.

If you save a file that is one byte long, it will take up 4 K on disk. If you save a file that is two bytes long, it will take up 4 K on disk. Space on disk is always allocated in 4 K chunks.

If you save a file that is 5 K, it will take up 8 K on disk. The size of the file is 5 K, but the amount of disk space it needs is 8 K, because space on the disk is always allocated in 4 K chunks.

The JPEG you are saving is 73.9 K. It will work on your Web site. Get Info says it is taking up 76 K because space on the disk is always allocated in 4 K chunks.

Use the Get Info command and look more closely at the Get Info window. You will see TWO sizes. One size is in bytes and is the true size of the file, which will be 73 K. The other size listed is the size it takes on disk, which will always be a multiple of 4 K.

There is nothing wrong. Your file is 73.09 K. You’re just getting confused because it takes up more space on the disk.

—
Photography, kink, polyamory, shareware, and more: all at http://www.xeromag.com/franklin.html

"Johan W. Elzenga" wrote in message

There is no need to do that. Even if the file takes a little more space on a certain hard disk, that doesn’t mean it has really grown in size. Look at the size in bytes, not at that ‘XXX KB on Disk’ in front of it. If the file was smaller than 75 KB, it will still be smaller than 75 KB when you upload it, even if it takes 76 KB on *your* disk because of those blocks.

Well, it’s a good idea for him to just go ahead and try – to see how much space it takes on the host drive, but keep in mind that the trend is to larger discs, therefore larger cluster factors. Perhaps the host measures the file size as other than size+cluster factor.