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Dissecting Save For Web feature - a problem for a VERY ADVANCED photoshop user


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benizm

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I am in need of advice from a real photoshop guru. Following is a brief explanation of my issue.

I have 5000 images in a large tree structure, and I need to reduce all of them to both 131x131 pixels and then 80x80 pixels whilst using the Save for Web feature. Save for web will make these images about 2kb to 4kb in size as opposed to Save As... which, on the lowest quality will save the image at about 20kb.

Now, due to this large tree structure, it would make sense to run an action on the entire folder and subfolders, right? The problem arises when recording an action and incorporating the Save for Web feature. One must specify which folder to save the optimized image into - one simply cannot just override the original file in the original folder.

I need to figure out exactly what the Save for Web feature does to the image to make it so small. I have found that one needs to change the colour profile from RGB to sRGB, but this does not let me Save As... to a 2kb file.

Can somebody please help me with doing a Manual "save for web" and outline each and every step needed to be done?

Thank you in advance...

-Ben
 
Welcome. 8))

benizm said:
Now, due to this large tree structure, it would make sense to run an action on the entire folder and subfolders, right? The problem arises when recording an action and incorporating the Save for Web feature. One must specify which folder to save the optimized image into - one simply cannot just override the original file in the original folder.
Click to expand...

You can't do this with just an action, you need to use the action in a batch, only then you can select a target folder.

Check out this thread: http://www.photoshopgurus.com/forum/index.php?topic=8511.0
 
Thank you for your response.

Creating actions and then executing then within a batch is what I do most of the day, so I'm very familiar with that feature. The problem is using Save For Web. Save As will let you override the original file and save it in the original folder. Save For Web will only let you specify a single folder to save all the images.

I am working with hundreds of folders and having to save every processed file into 1 folder then re-distributing them will be very time consuming.

I want to know the "Secret" behind the Save For Web feature, and how it can make images retain a good quality but being 10 times smaller than the lowest quality of the Save As option.
 
Okay so now i've come to the conclusion that Save For Web deletes all the meta data and exif information thus reducing the file size. This is the only explanation I can find.

What I need to know now is, can photoshop do this without using the Save for Web feature?
 
benizm said:
Save For Web will only let you specify a single folder to save all the images.
Click to expand...

Photoshop can't save the results in the target folder using the same folder structure of the source folder.

benizm said:
I want to know the "Secret" behind the Save For Web feature, and how it can make images retain a good quality but being 10 times smaller than the lowest quality of the Save As option.
Click to expand...

Secret? There is no secret. Let's be fair; how can you expect good quality with files that are 10 times smaller than the lowest settings of Save for Web (which already looks terrible), that's asking for the impossible don't you think?


benizm said:
Okay so now i've come to the conclusion that Save For Web deletes all the meta data and exif information thus reducing the file size.
Click to expand...

The main reduction comes from a lower jpeg setting, not from losing a few bits and bytes of meta or exif info.
 
Gaussian said:
Secret? There is no secret. Let's be fair; how can you expect good quality with files that are 10 times smaller than the lowest settings of Save for Web (which already looks terrible), that's asking for the impossible don't you think?

The main reduction comes from a lower jpeg setting, not from losing a few bits and bytes of meta or exif info.
Click to expand...

I disagree. I have just executed a test to demonstrate that the main reduction is not from a lower jpeg setting.

The first image is using the Save for Web function on 65 quality. The file size is 2.49kb.

The second image is using Save As on the 0 quality and is 28kb.

The third is the same as the Save As with 0 quality, but have used a program to remove the EXIF information. This one came out at 21kb.

Test results show that the Save for Web file size compared to the save as is significantly smaller, yet the quality is much better than Save As.

I thought it may be the EXIF info but it's not. Nor is it the quality setting. There is something else going on behind the scenes which I would like to know...
 
benizm said:
I disagree. I have just executed a test to demonstrate that the main reduction is not from a lower jpeg setting.
Click to expand...

You're wrong. The main reason why you see a difference like this is because of the rather small file you're working with, so the removal of EXIF data and Jpeg markers (you forgot those) will give the impression that most of the compression is not related to the Jpeg setting.

The reality is different.
I tested for you with a much larger image, first I cropped it to the size of the image you posted and saved:

save as with 0: 12kb
save for web with 65: 4kb

I returned to the original size and saved again:

save as with 0: 50kb
save for web with 65: 156kb

Which pretty much conforms what I said earlier; the main compression comes the JPEG settings, but only with very small images like yours it's obvious that the amount of exif data and jpeg markers comes close or exeeds image data, after which you will see the results you're seeing.
 
This doesnt answer my initial query though. How can i remove the EXIF data and the Jpeg markers (as you mentioned) manually in photoshop as an action to later be used in a batch so that I may mimmick the execution of the Save For Web feature thus being able to save over the top of the original source file in it's own folder within a massive folder structure? Surely if it can be done automatically, it can be done manually also right?

Keep in mind that there are 5000 files to do this to within 500 folders.
 
Like I said earlier, Photoshop can't save the results in the target folder using the same folder structure of the source folder, so I don't understand why you're so eager to use Save As, it has the same problem.
 
Also understand that the section "Save As" in automate, not only refers to Save As but also to Save for Web.
 
It should be quite easy to achieve what you want if you have Photoshop that supports scripting.

The only thing that I can see though, is that if you require two different sizes, that would require different file names,
this is no problem and anyone with scripting knowledge should be able to write a script for you do everthing in one pass.

Paul.
 

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