General discussion

PNG file save and save as, what happens?

Hello everyone Happy

I use Windows 7
I open paint and save a PNG file

The file created is file A

File A has the following properties
Created: 01.01.2018
Modified: 01.01.2018
Accessed: 01.01.2018

If I open file A in paint later, then what am I actually looking at?
File A?
A copy of the picture made by paint?
A copy of file A?
A cached file?

If I then press SAVE, the following happens:
The whole file is written anew? Is it a whole new file?
The old version of the file is being moved or copied to cache?

Then the following is added to the new file:
The created date remains the same and is written to the new file
The new modified date is written to the new file
The new accessed date is written to the new file

What remains from the old version of file A?

If I then press SAVE AS, what is different from SAVE?
The created date changes
What else?

How much data from earlier does a PNG file keep?
I have opened a PNG file in various software, to look at the metadata
I can only see the latest created, modified and accessed dates.
Does it only log the most recent dates?
Will it overwrite the date every time?
Does it log older dates from before?

Thanks a lot for answering

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Some answers

1. Your command is to open the file. But before going to the disk Windows might look if it's still in memory. Only Microsoft can tell if it does or not.
2. Save writes a file. If it happens to use the same location on the disk, you could say it's the same file that's updated. If it uses a different location, you can say it's a new file. Only Microsoft can tell if it does or not, depending on what factors.
3. Save as makes a new file. Nothing happens to the old file.
4. I wouldn't call it logging. It just writes some attributes of the file in the dictionary.

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Regarding som answers :)

If I reboot, the RAM is reset and the memory is lost, right?
So it is only in memory, if I open the file again?

When does it use the same location?
When does it use a different location?
But normally a file is written on the same cluster, or clusters that are close to eachother?
What if the file changes size, is it then written on another place on the disk?

When i press "save"
The whole file is written?
And what about the metadata, it is written again? All of it?

Post was last edited on November 30, 2018 2:14 PM PST

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More answers

I can only offer when to use "save as" versus "save". In any event, either may affect the time stamp. Some programs do create temp files while one is working on a document or photo but that depends on how that program is written. Now, when using Paint, you might want to use "save as" for one of these reasons;

1. You want a duplicate file in another location
2. You want to change the name of the file (also creates a duplicate)
3. You want to create a new file in another format such as a PNG to JPG so you can import it into some other document.

In some cases, you can see both a file creation date and the date it was last modified but this, again, depends on the program used to create or manipulate it. As for the time stamp, I don't find that to be of much use unless I've duplicated the file and want to open a specific revision of it.

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Choosing "Save" simply saves your work by updating the last saved version of the file to match the current version you see on your screen.

Choosing "Save As..." brings up a prompt to save your work as a file with a different name. For example, you might choose to save a document called "Paper - name. 3" as "Paper - name. 4". This way, you can save you file at different stages and keep multiple versions on your hard drive.

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Changes in PNG file

If you are clicking on save then whatever you change that save but if you want to change in date and other any word you have to add then you have to click on save as.this file has removed previous file.

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