File Size Discrepancy Between Photoshop & the Finder

Question

File Size Discrepancy Between Photoshop & the Finder

I'm trying to be as brief as I can, so here goes. The specific application (PS) is irrelevant, I think. This is about why an app shows one file size & the Finder shows a different file size. In this case, it's a huge difference, due to the file being an image.

I imported into PS CS, from a CD, an original image, which the Finder shows as 269.4 MB. The file format is TIFF, and the bit-depth is 16, not 8. The Finder shows it as a "TIFF Document." Now. I did a Save As and edited that as a master image file. So, I have two files: the original and the master.

I substantially cropped (deleted) pixels in the master file. So, at the same 16-bit depth, the master file should be smaller in size than the original. Right? However, the Finder shows the file to be 433.6 MB in size! Photoshop shows the file to be a more realistic 185.8 MB in size. Why is the Finder showing such a huge file size? Why is the Finder storing 247.8 MB more than I need? The Finder shows this file as an "Adobe Photoshop TIFF file," so there has been a change in format. The file is flattened; no layers, etc., are involved.

One clue could be that the Finder is storing the larger file size to accommodate Photoshop. If one multiplies 185.8 MB by 3, the result is close to the 433.6 MB figure. The 3 stands for the three color channels (red, green, blue) of each pixel (data element) in the image.

The original image, however, is stored correctly by the Finder. Photoshop and the Finder agree on the 269.4 MB file size. If the above scenario were true, the Finder would be storing the original file at three times the size as shown in Photoshop. In other words, there would be consistency in what the Finder is doing.

I suppose I could just ignore the discrepancy, but I have hundreds of images to process, and I don't want to have to go into PS every time to get a true reading of file sizes. The Finder should be accurate in doing that.

I may be in the wrong forum re: Photoshop, but here I think I can find some expertise re: the Finder, since the Finder's storing procedures are in question, to my mind. It's definitely an app/OS interface problem, as I see it. Simply, I edit a file downward in data, save it, yet the Finder saves it at a larger size.

G5 1.8GHz, 2.5GB RAM, 80GB HD, Seagate 320GB int. HD, LaCie 200GB ext. HD, Mac OS X (10.3.9), Beige G3 266 OS 9.2.2 A/V personality card

Posted on Sep 10, 2007 10:02 AM

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Answer 1

eww

Level 9

53,052 points

Sep 10, 2007 10:36 AM in response to David Werner1

Hi, David. Was the original TIFF file compressed, and did you Save As... without compressing the new file?

Working in PS CS2, I've just tried to replicate the phenomenon you describe, and I can't do it. Opened a 24.2MB 8-bit .psd file in CS2, saved it as a 16-bit uncompressed TIFF (48.5MB in PS, 48.6MB in the Finder), opened the 16-bit TIFF in CS2, cropped it and Saved As in same format (28.5MB in PS, 28.5MB in Finder).

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Answer 2

Sep 10, 2007 3:45 PM in response to eww

I thought I might have compressed the original file, so I checked its size on the CD. Its size (269.4 MB) is the same as the original file the Finder shows me, so I didn't compress it. I might have compressed the master file, & if I did, it was with LZW compression. However, on a separate occasion with a different file, I noticed that if I used LZW compression, the file actually increased in size!

I'm not going to use any compression when saving a file, because it's too easy to forget what I've done. There's no point in keeping an original file in compressed mode on Mac HD when that original is available on the CD. I guess I'm stuck with keeping the 433.6 MB master file on the Mac HD, as I put a lot of time & effort into editing it. I think "compressing" it with LZW caused the increase in file size, oddly enough. I do think you put your finger on the problem as one of compression.

As you seem skilled with PS, do you think a lot of cloning & healing brush might have added to the file size, even though I cropped the image? I wouldn't think so, as pixels are simply replaced by other pixels.

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Answer 3

eww

Level 9

53,052 points

Sep 10, 2007 7:23 PM in response to David Werner1

...do you think a lot of cloning & healing brush might have added to the file size, even though I cropped the image?

Yes, depending on your History settings. The more you work on an image, the more history it accumulates. The more different states and sanpshots you save in the History palette, the bigger the file gets as you work on it, because you're storing (within the file) complete information about the file's state before and after every individual change you make to it. What I don't recall is whether that all gets saved to the file in a Save As, or whether the history is flushed each time the file is Saved.

I should warn you that I am by NO stretch of the imagination a PS expert. I was still using PS 5.0.2 until last February, when I upgraded to CS2 (knowing it will be years before I have enough hardware horsepower to run CS3). I'm a rank beginner with CS2, and if someone else wants to jump in here and point out that I'm all wrong, it will be no surprise to me. And because I never used CS, I don't know whether what I'm describing in CS2 is even relevant here.

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Answer 4

Sep 11, 2007 7:53 PM in response to eww

Just want you to know I solved my problem. I read up on the History palette & when the image is closed, that info is discarded, except if a snapshot of a particular state is made. That snapshot is saved. I made no snapshots.

I did see I had a Histogram (Adjustment?) layer in addition to Background, which I hadn't noticed before, so I flattened the image. Dunce that I am, I did not do a Save, thinking that the change would be immediately reflected in the Finder, which of course, it wasn't. So, I did a Save As, and *the resulting file is identical in size to what PS shows*. I deleted the big file & now have a file in the Finder that agrees with PS. If I'd just have done a Save after flattening the file, I wouldn't have needed the Save As, but there you are.

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Answer 5

eww

Level 9

53,052 points

Sep 11, 2007 8:17 PM in response to David Werner1

Well, good. I took you at your word when you said the image had been flattened before saving, so I wasn't thinking about extra layers as a possible explanation. But I'm glad you figured it out on your own, and I thank you for straightening me out about the History palette and what gets saved. As I said, I'm glad to be corrected, and now I've learned something too!

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Answer 6

Sep 11, 2007 8:50 PM in response to eww

I was wrong about Snapshots being saved. I double-checked. PS manual: "Snapshots are not saved with the image--closing an image deletes its snapshots." Sorry for the bad info.

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