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  • What’s On That Old SD Card You Gave Away?

    I recently bought a second-hand camera – but this is not specific to photography (but perhaps particularly relevant). The seller threw in an old SD card which was nice of them (although unnecessary for me).

    After doing the photo thing with the new-to-me camera, and having carefully replaced the SD card, it occurred to me that I could test a file recovery tool to see if there was any previously shot photos on the card.

    Using photorec, I fired it off and came back 30m later – not because it’s particularly slow but I have spent far too much time watching the equivalent of a progress bar, and I would rather get on and do something useful.

    By the time I came back, it had recovered in excess of 1,000 images and videos. It turns out to be probably the most boring collection of photos you can imagine – an ordinary collection of family (not your own) photos would be interesting in comparison.

    I won’t be including any of those recovered photos here because that would be unprofessional and potentially embarrassing to the camera seller (although they would most likely never find out). 

    But you can easily imagine how such a recovery could be potentially embarrassing; even distressing. We usually choose whether a photo should be made public or not.

    So how do you protect such things from happening? Is it sufficient to format a card in camera?

    No it isn’t. Tools such as photorec are designed to recover images from cards where the images have been deleted or when the card has been formatted. Surprisingly enough, formatting a card does not overwrite all of the data blocks on a storage device; it merely replaces the data structures that allows an operating system to find files with a new blank structure.

    So what are the solutions to keep your private photos to yourself?

    It should be emphasised that this is advice intended to protect you from personal embarrassment; if there are legal or risk to life issues involved, seek professional advice.

    The first rather obvious solution is to never give away or sell old cards; if you want to dispose of the cards, destroy them. It is not as if you could recover much by selling them – who wants a 5-year old 512Mbyte SD card?

    If you do want to let others use your old cards, then use a special utility to destroy the contents completely; optionally (but nice for the recipient) is to then format the cards afterwards.

    If you are using Windows (or macOS although the following Linux recipe can be adapted), then you will need a tool such as SafeWiper. There are those who claim that Windows format can do the job, but I wouldn’t trust it – the “quick format” option is the default which definitely doesn’t erase the data from the disk, and I have not personally checked that a “slow format” really removes the data beyond recovery with normal tools.

    Whatever method you choose, check, double-check, and triple-check that the device you are erasing really

    The first step under Linux is to identify the block device path to erase. You may well find that your SD card is automatically mounted when you plug it in. So running df from the command-line will give you a device path (/dev/sdb

    But to double check, run lsblk 

    ✓ mike@Michelin» lsblk -o NAME,FSTYPE,MOUNTPOINT,VENDOR,MODEL,SIZE | grep -v loop 
NAME                    FSTYPE      MOUNTPOINT                      VENDOR   MODEL              SIZE
sda                                                                 ATA      SAMSUNG MZNTY128 119.2G
├─sda1                  vfat        /boot/efi                                                   512M
├─sda2                  ext4        /boot                                                       732M
└─sda3                  crypto_LUKS                                                             118G
  └─sda3_crypt          LVM2_member                                                             118G
    ├─ubuntu--vg-root   ext4        /                                                         114.1G
    └─ubuntu--vg-swap_1 swap        [SWAP]                                                      3.9G
sdb                                                                 Generic  USB  SD Reader     3.8G
└─sdb1                  vfat        /media/mike/disk                                            3.8G

    Note that how we have “USB SD Reader” alongside /dev/sdb and that it’s size is just 4Gbytes. So we have three confirmations that this is the device we want to erase.

    To erase it, first we unmount it, run a hdparm command to erase it, and erase it a second time :-

    ✓ mike@Michelin» umount /dev/sdb1
✓ mike@Michelin» sudo hdparm --security-erase NULL /dev/sdb
security_password: ""

/dev/sdb:
 Issuing SECURITY_ERASE command, password="", user=user
SG_IO: bad/missing sense data, sb[]:  70 00 05 00 00 00 00 0a 00 00 00 00 20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
SG_IO: bad/missing sense data, sb[]:  70 00 05 00 00 00 00 0a 00 00 00 00 20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
SG_IO: bad/missing sense data, sb[]:  70 00 05 00 00 00 00 0a 00 00 00 00 20 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
✓ mike@Michelin» sudo dd if=/dev/zero of=/dev/sdb bs=64M

    Whilst we’re waiting for the “dd” command to finish writing zeros all over the SD card, why are we erasing this twice? 

    We’re using hdparm

    And I then suggest using the old slow method of “dd” as well because there is nothing wrong with being cautious in this area.

    Misty Trees

  • Is The Print Better Than The Web?

    To use a phrase I’m known for: Well yes and no.

    There is no doubt that nothing quite beats a huge (A3+ or bigger) print of a really good quality landscape photo. But what proportion of all the world’s photographic images are available as such a print?

    Probably a tiny minority; in the past when everyone shot film, most photographs were developed as prints 5″ x 7″ (or similar) which is tiny. At an estimate of 200dpi (which is probably an overestimate of the average print), that is a resolution of 1000×1400.

    Now if I compare this with pictures shown on the web on my laptop screen (a rather titchy display), it compares rather favourably – a Facebook photo capture was around 850×850, and an EyeEm photo capture was 1212×900. Of course it is also shown somewhat larger – the laptop screen is 13″.

    And on my main desktop screen (a very elderly 30″ screen), the same two pictures are far bigger and in a higher resolution – 1028×1300 for the Facebook picture and 1200×1800 for the EyeEm photo.

    And finally, on my 4K TV, the photos are shown at only 2/3 (very roughly) the resolution of the original files, and far, far bigger.

    Yes the display pitch is less, but the size is far larger and unless you have spectacular close vision you will be able to see far more detail with a screen image than an average print.

    Again I say that this is not intended to bash prints – in many ways a photographic image isn’t finalised until it has been printed, and a really good print at 300dpi and printed large is far better than the screen. Even before you consider the permanence of the print.

    This is aimed at those who snootily dismiss low-end photographic equipment as being “only suitable for the web” – they may be surprised that even relatively modest screens can compare favourably with 5×7 prints and it won’t be long before even larger prints are surpassed. 

    Hill Conquered

  • Why Does Tilde (~) Mean Home In Linux?

    If you use the Unix or Linux command-line, you may very well wonder about the origins of some of the “special” characters. One of those is tilde (~) which is expanded by the shell into “home” :-

    ✓ mike@Michelin» echo $HOME                        
/home/mike
✓ mike@Michelin» echo ~
/home/mike
✓ mike@Michelin» echo ~root
/root

    This doesn’t of course work in general; just in the shell.

    But where did this usage originate?

    As it turns out, it was the markings on the keyboard of the ADM3A terminal :-

    If you used Unix in the late 1970s/1980s, you may very well have used the ADM3A terminal and it seems that those who added the tilde feature to the Unix shell were amongst the users.

  • They Died For Our Freedom …

    Horseshit.

    Normally on Remembrance Sunday, we remember the dead of all wars, but this one is a bit special – it’s exactly 100 years since the armistice that brought the killing phase of World War 1 to an end.

    Around this time of year, there are often those who make grand pronouncements about the sacrifices those who fought made for some sort of noble goal – our freedom, the freedom of others, to defeat a really nasty enemy.

    None of that applies to those who died in WW1; some of them may have felt they were fighting for their freedom (and our freedom). But they really fought because of the 19th century equivalent of mutually assured destruction.

    Austria-Hungary and Serbia fought because of the assassination of a single man. Russia fought to support Serbia; France fought to support Russia; Britain fought to support France. And Germany fought because Austria-Hungary fought. This gross over-simplification happened remarkably quickly – all of the declarations of war occurred within about 1½ weeks.

    So no great debate on the aims and goals of what the war was for then.

    So whilst those who fought (and in some cases died) in wars are not to blame, not all wars were fought for good reasons – certainly you’ll find it hard to find a good reason for WWI. 

    Light’s Shadow

  • Terrorism: The Alt-Right’s Hypocrisy

    There are plenty of arguments to be had with the alt-right, beginning and ending with their repulsive policies. But this post isn’t about that …

    I’ve encountered the alt-right’s asinine attitude to political violence before, but I was reminded about it again this morning (obviously some time ago now) with the news that someone had sent George Soros, Hilary Clinton, John Brennan, and Barack Obama a letter bomb.

    Yet the alt-right would have us believe that it is the left who are more violent than the right. And both less violent than the Islamic extremists. Turns out that is not the case.

    It is not even close. The overwhelming majority of terrorist attacks in the US are perpetrated by the right-wing.

    The bête noire of the far right – Antifa? Never murdered anyone; in fact if you add together all of the political murders of the far left in the US over the last 10 years it adds up to 7-8 people (2-3%) whereas the far right are responsible for over 70% of the murders.

    Antifa may well be more violent than you are happy with; their purpose after all is to tackle the fascists, which isn’t done without breaking heads. But they don’t intentionally go out to murder people – so don’t be taken in by the main stream media’s portrayal of them when they are busy denying that the far right (and “alt right”) are far more violent.

    Even more than those evil islamic terrorists (who are pretty much the same as the far right).

    Denying your own side’s violent actions and pretending it is the other side who are really the violent ones is classic gaslighting.

    Ruins