size matters

Engaged ,
Jul 21, 2022 Jul 21, 2022

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I processed some scenics that are scans from slides, full frame, in topaz AI software.  Though the tiffs were originally saved compressed as LZW, they come out much larger, without the compression.  My website accepts up to 64M, and many are over 100M, eg example 143M.  I had a compress action but when it goes to save it says it will be larger with lavers.  I look and there is only 1 layer, that says layer 1.  I flatten anyway and it becomes background and saved, it becomes ~ 100M.  So then I go back to compress using LWZ and it is back to 143M.  I posted a similar thread about trying to reduce the size in 'image size' and also had images coming out larger instead of smaller when reduced there. What is going on? I din't want to have to go over every image and reduce each's measurements. When there were only a few I would do so and save with a minus (-) put after the name, but this is a lot of trouble when so many are coming out gigantic.

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Adobe Community Professional ,
Jul 21, 2022 Jul 21, 2022

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Save as JPGs and to the dimensions you need and experiment with compression to get the smallest file size without too much image deterioration.

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Adobe Community Professional ,
Jul 21, 2022 Jul 21, 2022

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Are these 16-bit files by any chance?

LZW compression will increase the file the size of 16-bit files.

ZIP compression will decrease the file size somewhat.

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Engaged ,
Jul 22, 2022 Jul 22, 2022

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Where do I see the bit info?

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Adobe Community Professional ,
Jul 22, 2022 Jul 22, 2022

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Image > Mode

Screenshot 2022-07-22 at 11.07.14.png

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Adobe Community Professional ,
Jul 22, 2022 Jul 22, 2022

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image.png

 

To learn more about bit depth, see What is a digital image? 

About Tiff compression: File formats 

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Engaged ,
Jul 22, 2022 Jul 22, 2022

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Yes, 16 bits. I alwys save from my raw files, tiffs with LZW.  Likewise for slide scans. So for example a slide scan image which was originally only 37mg, well within my website limit of 64M, comes out of Topaz Photo AI at 110M. Dimensions are the same in Image Size.  So, since I don't want to use jpeg, I actually have to shrink the size of the picture considerably to be under 64G.

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Adobe Community Professional ,
Jul 22, 2022 Jul 22, 2022

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Well, in that case, don't use LZW compression, use ZIP compression instead.

What exactly will these tiffs be used for?

If no further editing will be done to these files, you can convert (copies of) them to 8-bit and save them with LZW compression.

That will save you a lot of space, since 8-bit files are half the size of 16-bit files, and LZW compression is more efficient on 8-bit files than ZIP compression on 16-bit files.

 

The recommended workflow is to do all editing in 16-bit mode, and keep these files as master files.

You can then save 8-bit tiffs or jpgs as needed for other purposes.

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Engaged ,
Jul 22, 2022 Jul 22, 2022

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So after reading that, I just did a test on a RAW file and saved both ways.  For years I've been saving as LZW thinking I was saving space and now find out I was increasing it, about double. Tens of thousands of files thus saved this way. I will save uncopressed in the future, but I see that saving compressed ones as uncompressed doesn't change, I don't want to use zip as images go to my website or to publishers who don't want that.  

 

I've been reducing dimensions in image size and then saving the image with a minus (-) inserted in the name so I know it is reduced and then uploading that,  Is there any way to use an action to do this on a whole batch or would they all wind up with the same name?

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Adobe Community Professional ,
Jul 22, 2022 Jul 22, 2022

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I assume that you are posting tiffs you have finished editing to your website for download via a link, and to publishers for printing.

If that's the case, you definitely don't want to use 16-bit files, use 8-bit.

And with 8-bit, you get very efficient LZW compression.

If you haven't already done so, please read the articles I linked to.

 

As for renaming files, the free utility ReNamer will do this for you.

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Engaged ,
Jul 22, 2022 Jul 22, 2022

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So after looking at more image modes, it seems that I saved and processed in only 8 bit mode, and saved as LZW tiffs.  But after Topaz Picture AI worked on them, they became uncompressed and 16 bit.  Is there any advantage to making an 8 bit file 16 bits?  It can't add more data that's already gone,  just made it bigger, correct?  Or is it that the LZW compression save reduced them from 16 bits to 8 and the Topaz just restored it, but again, was the data lost irettrievably and the larger size has no merit?

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Adobe Community Professional ,
Jul 22, 2022 Jul 22, 2022

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I'm not familiar with Topaz Picture AI, but the three Topaz plugins I use, Sharpen AI, DeNoise AI and Gigapixel AI do not have an option to change the bit depth. Feed them 8-bit files, and 8-bit files are returned.

The LZW compression cannot cause this conversion either, so you must somehow have converted them to 16-bit yourself.

And you're right in assuming that there is no advantage to converting an 8-bit file to 16-bit.

 

IMO, there is no disadvantage to using Tiff. It is more widely supported than PSD, and also has slightly better compression, as far as I can remember from some tests I did years ago.

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Adobe Community Professional ,
Jul 22, 2022 Jul 22, 2022

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And you're right in assuming that there is no advantage to converting an 8-bit file to 16-bit.


By @Per Berntsen

 

Not as it is, but there is if you're going to do further work on it.

 

8_16_bit.png

 

This is a real-life example of adjusting an 8 bit file, vs. converting to 16 and doing the same adjustment, then converting back to 8 (refreshed, not cached, histograms).

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Adobe Community Professional ,
Jul 22, 2022 Jul 22, 2022

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And quit using TIFF, PSD is generally more efficient. Or just put JPEG online.

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