Solved Why does the File size of Tiff image reduce when I add a tag?

[PeterP78211]

I have scanned in a load of photo slides as tiff images. I have found that, if I add one or more tags to the images using Windows Explorer the file size per image decreases from about 5MB to 4MB. There is no noticeable decrease in resolution. Why does the size decrease?

 

[kingscurate]

Could win explorer be saving the image with some compression when adding the tag.

 

[PeterP78211]

That's what I'm trying to find out. But there doesn't seem to be any visual difference in the picture when zoom in. To me it doesn't make sense that, having added information to the image, the file size drops,

 

[mitchell65]

If you Google "TIFF" you will see that the "T" stands for "Tagged". TIFFS contain default tag lines and when you add a tag it might be shorter than the default allowance. Lets say that the default allowance in 8kb in size and your tag is only 4KB then if the original file size was 5MB the new tag size might just bring the total file size down a whisker but below 5MB. That's why it shows as 4MB.
I'm no expert on this but I do find it better to use PNG files. This like TIFF is a lossless format but has less complications than TIFF's

 

[PeterP78211]

Thanks for the reply. I had wondered if, adding a specific tag freed up default allocated space. But the file size has dropped from 5076kB to 4081kB which is a lot. In some cases the drop has been even bigger...

 

[mitchell65]

Hi Peter
I can't give a techie reason why tiffs do this size alteration. I have noticed it can go up or down by an appreciable amount for no apparent reason but I'm sure there is one somewhere. This is really why I advocate the use of PNG's. This is a lossless format which means there is no compression and subsequent loss of quality plus like for like it usually saves to a much smaller file size than Tiffs. I have just scanned an image and saved it to TIFF and PNG. Both the exact same quality but the TIFF is 13.7MB and the PNG is 10.7MB. If you are scanning a lot of images that can be a huge saving in ovewrall space. If you have a lot of TIFF's and wanted to rename as PNG's then The free software Irfanview does a very good batch conversion. Much better than Photoshop, I have found!

 

[Faladu]

I have been using Irfanview 10 years+, love the speed and features, and free.

Great for reducing size of pictures, minor editing, switching them to grayscale, etc etc.

 

[camillem210]

Hi Peter
I can't give a techie reason why tiffs do this size alteration. I have noticed it can go up or down by an appreciable amount for no apparent reason but I'm sure there is one somewhere. This is really why I advocate the use of PNG's. This is a lossless format which means there is no compression and subsequent loss of quality plus like for like it usually saves to a much smaller file size than Tiffs. I have just scanned an image and saved it to TIFF and PNG. Both the exact same quality but the TIFF is 13.7MB and the PNG is 10.7MB. If you are scanning a lot of images that can be a huge saving in ovewrall space. If you have a lot of TIFF's and wanted to rename as PNG's then The free software Irfanview does a very good batch conversion. Much better than Photoshop, I have found!

I agree .PNG is superior to TIFF. I suggest convert the formats by Irfanview or any other image converter with a tiff prccessing function.

 

[logicearth]

It probably was a restructuring of the file, removing a lot of blank "white space" (which could be any junk data) which didn't need to be there. That would be my guess. Clarifying, it removed excess junk data.