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Thread started 22 Feb 2018 (Thursday) 14:36
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How do I delete photos from memory cards?

 
Choderboy
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Feb 23, 2018 07:21 |  #16

John from PA wrote in post #18570314 (external link)
Much of what Wilt wrote came from Wikipedia, see https://en.wikipedia.o​rg/wiki/Disk_formattin​g (external link).

Why the need to overwrite everything exists is beyond me but if the OP is familiar with Windows you can use DISKPART to wipe the disk. The procedure is at https://www.howtogeek.​com …on-and-capacity-problems/ (external link) but follow the steps carefully.

There's a reason I can think of. Photos of an intimate nature....
Other 'above board' reasons, small kids in the bath, workplace photos.


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Left ­ Handed ­ Brisket
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Feb 23, 2018 08:13 |  #17

Choderboy wrote in post #18570329 (external link)
There's a reason I can think of. Photos of an intimate nature....

you might be right, i just noticed Perfectly Frank's title!!!

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ewwwwwww.


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mcoren
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Feb 23, 2018 08:20 |  #18

The thing about Flash memory is that it doesn't store 1s and 0s, it stores charge. When a Flash memory cell is read, the amount of charge is interpreted as a 1 or a 0. Even if you "erase" a cell, it is possible for somebody with the right equipment (e.g. law enforcement) to measure residual charge and make a statistically significant guess of what value it once held.

Flash memory cells also have a limited number of write cycles. These days they number in the hundreds of thousands, but they're still limited (the first time I designed with Flash memory, that number was more like a couple of thousand writes). In order to maximize the life of the entire chip, the on-chip drivers will use write leveling so the writes are spread across the array. Bottom line: If you write to the same location from the outside, internally it may go to different places on the array. Apple removed the secure file erase capability from macOS X a couple of years ago for this very reason, because it wasn't reliable with SSDs.

Overwriting an entire device might be more successful in making sure you hit the data you want to hit. The most secure utilities I've seen will use multiple passes (5 or 7) with pseudorandom data.

My advice to the OP is to format the cards as best as you can with the utilities you have (or can reasonably get) and don't worry about it. I would think most people around here who buy used memory cards just want to use them for their own purposes.

In his first post, the OP talks about selling some cards for "a few bucks", so it doesn't sound like this is a significant amount of money. If you're really concerned about somebody recovering what was once on the cards, don't sell them. Grind them up in a good quality paper shredder. Or smash them to bits with a hammer.

Mike


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Wilt
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Feb 23, 2018 08:37 |  #19

mcoren wrote in post #18570282 (external link)
Can you provide a source for this please?


https://en.wikipedia.o​rg/wiki/Disk_formattin​g (external link)

It may not be 100% accurante source of information, but there is plenty of public viewing of what is published that folks do submit the identification of grossly wrong/outdated information.and it is updated as standards change over the years.


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Sibil
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Feb 23, 2018 12:20 |  #20

Choderboy wrote in post #18570329 (external link)
There's a reason I can think of. Photos of an intimate nature....
Other 'above board' reasons, small kids in the bath, workplace photos.

In that case I would simply physically destroy the cards instead of worrying about permanently deleting files.




  
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John ­ from ­ PA
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Post edited 4 months ago by John from PA. (3 edits in all)
     
Feb 23, 2018 17:10 |  #21

Choderboy wrote in post #18570329 (external link)
There's a reason I can think of. Photos of an intimate nature....
Other 'above board' reasons, small kids in the bath, workplace photos.

My point is over writing by firing off images or a similar write operation is totally unnecessary. A low level format would make everything essentially unrecoverable. We have someone on these forums in the industry, "eelnoraa". I've quoted his comments relative to a low level format (LLF) from the thread at https://photography-on-the.net …read.php?t=1311​586&page=2.

eelnoraa wrote in post #17240044 (external link)
Contrary to low level format in HDD, LLF in SD card does NOT wipe the entire card and fill "0". If it does, it will take minutes or more to LLF a 128GB SD card. we know it doesn't take that long.

A LLF for SD is erasing the control and file sytem area of the SD card. Now this area is NOT the file system area used by Windows or camera. It is the file system used by the SD controller. So after LLF, the SD card will still contains the 0s and 1s, but the controller itself don't know how to interpret the data. They are all just a bunch of random 0s and 1s. If you have a good enough software, you can read the RAW content from the NAND and reconstruct the data. I don't know of a software like this in a consumer market.

So just do a low level format in camera and be done with it!




  
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joeseph
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Feb 23, 2018 17:43 |  #22

Tom Reichner wrote in post #18570041 (external link)
I am not sure that I understand why it would be so essential to ensure that the images are entirely deleted from the cards. I mean, if you format, then they are removed for all practical purposes. . The only way in which they would remain would be for impractical purposes, such as someone using data recovery software. . So what?

I checked out your Flickr site to see what kind of photos you normally take, and there isn't anything there that I would think is the kind of stuff that would normally be stolen and exploited. . What is it that you are so afraid of when it comes to somebody being able to gain access to your old, deleted images? . What would somebody want with them? . What would somebody do with them that would be so harmful to you?

I just don't understand why this would be such a big deal, and any explanation would be appreciated.


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The sort of photos that the OP may not want to be recoverable from cards would be exactly the sort of photos that are not on his Flikr...
reasons for this could be anything from being commercial to being personal or intimate.

Having done some card recoveries before, I can say it is often surprising how old some of the recovered shots are!

A number of businesses I deal with, dispose of their IT gear very haphazardly, whereas some are quite clinical - destroying hard drives etc. rather than attempt to "clean" them.

I bought a firewall recently that still contained a full configuration including usernames & hashed passwords, that had been in service by a large betting agency [fools!]

As regards deleting photos, totally filling the card with junk files then deleting & repeating the process a couple of times would suffice for me...


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Choderboy
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Feb 24, 2018 02:25 |  #23

joeseph wrote in post #18570695 (external link)
The sort of photos that the OP may not want to be recoverable from cards would be exactly the sort of photos that are not on his Flikr...
reasons for this could be anything from being commercial to being personal or intimate.

Having done some card recoveries before, I can say it is often surprising how old some of the recovered shots are!

A number of businesses I deal with, dispose of their IT gear very haphazardly, whereas some are quite clinical - destroying hard drives etc. rather than attempt to "clean" them.

I bought a firewall recently that still contained a full configuration including usernames & hashed passwords, that had been in service by a large betting agency [fools!]

As regards deleting photos, totally filling the card with junk files then deleting & repeating the process a couple of times would suffice for me...

Bingo! Absolutely no reason to assume someone's Flickr gallery contains every photo or type of photo someone takes.

Something I have found is when using a photo computer at a printers, even though I have done a Quick format of a memory card and then copied only a few photos that I want printed, the computer finds very old photos!
(These photos are not seen by windows)


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DesolateMirror
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Feb 24, 2018 04:45 |  #24

Bassat wrote in post #18569964 (external link)
Google 'recuva'. It is a file recovery program from Piriform. There is a free version. It has a 'secure erase' feature. I've been using it for years without issue.

This is the best option, there are lots of other free and paid programs that will securely wipe data, just make sure you don't select your hard-drive.




  
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Wilt
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Feb 24, 2018 10:03 |  #25

Choderboy wrote in post #18570940 (external link)
Something I have found is when using a photo computer at a printers, even though I have done a Quick format of a memory card and then copied only a few photos that I want printed, the computer finds very old photos!
(These photos are not seen by windows)

That is because a Quick Format will erase the indexes/addresses of the partition table. It will not erase the actual data an those locations.

According to Microsoft, they altered the format behavior in Windows as of Win Vista
https://support.micros​oft.com …in-windows-vista-and-late (external link)


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Perfectly ­ Frank
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Feb 24, 2018 15:04 |  #26

Choderboy wrote in post #18570329 (external link)
There's a reason I can think of. Photos of an intimate nature....
Other 'above board' reasons, small kids in the bath, workplace photos.

C'mon, Choderboy, don't spill the beans! I didn't want that bachelor party incident to get out. Let's not go there. ;-)a


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John ­ from ­ PA
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Feb 24, 2018 16:49 |  #27

DesolateMirror wrote in post #18570978 (external link)
This is the best option, there are lots of other free and paid programs that will securely wipe data, just make sure you don't select your hard-drive.

What makes it "best". We are likely talking about an OP with limited computer skills.

As I said before a simple low level format in camera will basically wipe the card; no complication necessary. See https://digital-photography-school.com …of-cleaning-memory-cards/ (external link) and scroll down to the section on low level formatting.




  
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RDKirk
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Feb 25, 2018 08:54 |  #28

Wilt wrote in post #18570162 (external link)
Indeed...

"Low-level formatting (i.e., closest to the hardware) marks the surfaces of the disks with markers indicating the start of a recording block (typically today called sector markers) and other information like block CRC to be used later, in normal operations, by the disk controller to read or write data. This is intended to be the permanent foundation of the disk, and is often completed at the factory..."

"User instigated low-level formatting (LLF) of hard disk drives was common for minicomputer and personal computer systems until the 1990s. IBM and other mainframe system vendors typically supplied their hard disk drives (or media in the case of removable media HDDs) with a low-level format. Typically this involved subdividing each track on the disk into one or more blocks which would contain the user data and associated control information. Different computers used different block sizes and IBM notably used variable block sizes but the popularity of the IBM PC caused the industry to adopt a standard of 512 user data bytes per block by the middle 1980s.

Depending upon the system, low-level formatting was generally done by an operating system utility. IBM compatible PCs used the BIOS, which is invoked using the MS-DOS debug program, to transfer control to a routine hidden at different addresses in different BIOSes"

"Today, an end-user, in most cases, should never perform a low-level formatting of an IDE or ATA hard drive, and in fact it is often not possible to do so on modern hard drives because the formatting is done on a servowriter before the disk is assembled into a drive in the factory."

But then...

"Some modern formatters wipe hard disks with a value of 0x00 instead, sometimes also called zero-filling, whereas a value of 0xFF is used on flash disks to reduce wear. The latter value is typically also the default value used on ROM disks (which cannot be reformatted). Some advanced formatting tools allow configuring the fill value.[nb 7]

One popular method for performing only the zero-fill operation on a hard disk is by writing zero-value bytes to the drive using the Unix dd utility with the /dev/zero stream as the input file and the drive itself (or a specific partition) as the output file.[16] This command may take many hours to complete, and can erase all files and file systems.

Another method for SCSI disks may be to use the sg_format[17] command to issue a low-level SCSI Format Unit Command.

Zero-filling a drive is not necessarily a secure method of erasing sensitive data[not in citation given], or of preparing a drive for use with an encrypted filesystem.

We had to do true low level formatting on my brand new hard drives back in the day because it was necessary.

Today, however, my cameras and audio recorders have a "low-level format" option on the menu for the memory cards. I doubt it's doing the same thing as the true low-level format of the past. It takes a bit longer than the quick format...but nowhere near as long as the true low-level format of the past. I'm not actually sure what it does.




  
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John ­ from ­ PA
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Feb 25, 2018 10:40 |  #29

RDKirk wrote in post #18571834 (external link)
Today, however, my cameras and audio recorders have a "low-level format" option on the menu for the memory cards. I doubt it's doing the same thing as the true low-level format of the past. It takes a bit longer than the quick format...but nowhere near as long as the true low-level format of the past. I'm not actually sure what it does.

See my post above, #21, for what it does with respect to an SD card.




  
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Mar 12, 2018 09:01 |  #30

Bassat wrote in post #18569964 (external link)
Google 'recuva'. It is a file recovery program from Piriform. There is a free version. It has a 'secure erase' feature. I've been using it for years without issue.

Is secure erase the equivalent of low level format or is it something deeper?


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How do I delete photos from memory cards?
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