Tag Archives: holga

ASCII camera with the Holga 120d

So now I’ve finished my digital Holga project, one of the things I wanted to do was to get a bit creative with it – so here’s my first attempt at an ASCII art generating camera.

Holga 120d ASCII text image
High contrast images work best.

This uses the ASCII art script written by Steven Kay, please visit his blog to find out more – I’ve modified the original script to use the python picamera library – this helps speed up the image resize. There’s also a timestamp added to the text file which uses the same script I wrote about in my previous Holga post.

If you just want to run Steven Kay’s script you’ll need the python imaging tools – install with

sudo apt-get install python-imaging

Here’s my modified script:

'''
ASCII Art maker
Creates an ascii art image from an arbitrary image
Created on 7 Sep 2009

@author: Steven Kay
'''

import time
import picamera
from PIL import Image
import random
from bisect import bisect

# greyscale.. the following strings represent
# 7 tonal ranges, from lighter to darker.
# for a given pixel tonal level, choose a character
# at random from that range.

greyscale = [
            " ",
            " ",
            ".,-",
            "_ivc=!/|\\~",
            "gjez2]/(YL)t[+T7Vf",
            "mdK4ZGbNDXY5P*Q",
            "W8KMA",
            "#%$"
            ]

# using the bisect class to put luminosity values
# in various ranges.
# these are the luminosity cut-off points for each
# of the 7 tonal levels. At the moment, these are 7 bands
# of even width, but they could be changed to boost
# contrast or change gamma, for example.

zonebounds=[36,72,108,144,180,216,252]


#take photo

with picamera.PiCamera() as camera:
                        camera.capture('image.jpg');

# open image and resize
# experiment with aspect ratios according to font


im=Image.open(r"image.jpg")
im=im.resize((160, 75),Image.BILINEAR)
im=im.convert("L") # convert to mono

# now, work our way over the pixels
# build up str

str=""
for y in range(0,im.size[1]):
    for x in range(0,im.size[0]):
        lum=255-im.getpixel((x,y))
        row=bisect(zonebounds,lum)
        possibles=greyscale[row]
        str=str+possibles[random.randint(0,len(possibles)-1)]
    str=str+"\n"

print str

date_string = time.strftime("%Y-%m-%d-%H:%M:%S")

text_file = open('image' + date_string + '.txt', "w")
text_file.write(str)
text_file.close()

There are lots of settings to tweak – the image above was generated by the script – and bear in mind this is designed to be viewed with black text on a white background. Perhaps I’ll see if I can dig out an old dot matrix printer from somewhere.

For a blog of ‘photos’ updated whenever I take them and am in range of WiFi check out:

http://holga120d.blogspot.co.uk/

This emails the ASCII art in HTML format to blogger whenever I take a photo (and the Pi Holga is in range of the internet).

For more about the Digital Holga check out my previous blog posts on the hardware and building the case.

Digital Holga part 3 – taking photos with the inputs

This is my follow up to my previous posts about building a digital camera out of a Raspberry Pi Model A and a medium format Holga 120 film camera.

My aim being to build a hackable portable digital camera which hopefully would be able to capture images not possible with a normal digital camera, and to recapture the unpredictable spirit of film cameras (without the expense of the chemicals).

In my first post I fitted a Raspberry Pi model A and camera board into a hollowed out Holga 120. The Holga’s plastic construction makes it easy to work with and it’s roomy enough to accommodate a Pi without having to remove components from the board.

Pi camera case with Pi fitted
Here it’s sitting in it’s case. Snug.

In my second post I added the final inputs to the Holga case – a rotary selector switch with 3 positions, a push button switch on the side (with a trigger input on the bottom) and a power switch. I added a filter adapter to the front lens and I also took a few pictures by remotely triggering commands on the Pi.

Holga 120d Raspberry Pi Camera Case
Here’s the 3/4 view with the big clunky switch. It now switches the mode of the camera.

I’ve now connected up the switches and added 2 LEDs to the Raspberry Pi, making the Holga 120d a practical portable digital camera.

The rotary switch combined with the trigger switches effectively gives the Holga 120d 3 input buttons. The 2 LEDs (blue and orange) indicate the ‘mode’ the camera is in when I push the shutter button.

Each of the 3 ‘modes’ is programmable – at the moment I have 2 set up – one takes a photo which is saved to the Pi’s SD card, and the other performs a safe shutdown. It’s possible to add any command to the python script – and I’m working on an additional artistic mode which I’ll detail in a later blog.

I soldered all the inputs & the 2 LEDs to a Slice of Pi Breakout Board – these are available for around £5 and fit neatly over the Raspberry Pi without taking up too much space.

Raspberry Pi Holga 120d internals
Bit of a cram, but it all fits.
Holga 120d LED viewfinder
These light up to tell you the mode the camera is in.

From the board leading to the case, the green wires are to the push switch and trigger input, the 3 red wires & black to the right lead to the rotary switch and the red and black pairs lead to the LEDs.

The yellow wires just out of shot are to the flash hot-shoe. I did consider connecting this using an opto-isolator LED and there this space to do this at a later date.

There is also (just) about enough space to add a real time clock module – I used the Adafruit DS1307 Real Time Clock which connects to the 5v, GND, SDA and SQL pins on the slice of pi board. I followed Adafruit’s instructions (leave the resistors off the board!) and it works well.

The LEDs themselves slot into the viewfinder and light up according to the position of the switch. So in mode 1 the blue LED lights up, 2 both LEDs light and in 3 just the orange LED. This gives a bit of useful feedback to show that everything is working properly and the Pi is taking pictures when you click the shutter button.

For an easier to understand diagram – here’s the circuit laid out in Fritzing.

GPIO 23,24 & 25 are the inputs, with GPIO 17 and 18 driving the 2 LEDs. The switch at S2 is the rotary selector switch.

I used 330 ohm resistors for the LEDs and 10K resistors for the GPIO inputs.

Holga 120d wiring schema
Try on a breadboard first

 

The code I used is really simple.

Make sure you’ve run sudo apt-get update and have installed the Camera py modules first.

#!/usr/bin/env python

import time
import picamera

from time import sleep
import os
import RPi.GPIO as GPIO


GPIO.setmode(GPIO.BCM)
GPIO.setup(23, GPIO.IN)
GPIO.setup(24, GPIO.IN)
GPIO.setup(25, GPIO.IN)
GPIO.setup(17, GPIO.OUT)
GPIO.setup(18, GPIO.OUT)

while True:
        if ( GPIO.input(23) == False ):
                print('Orange: Taking photo')
                GPIO.output(17, True);
                date_string = time.strftime("%Y-%m-%d-%H:%M:%S")
                with picamera.PiCamera() as camera:
                        camera.capture('image' + date_string + '.jpg');
                sleep(2);
                GPIO.output(17, False);
        if ( GPIO.input(24) == False ):
                print('Blue')
                GPIO.output(18, True);
                os.system("sudo shutdown -h now")
        if (GPIO.input(25) == False):
                print('Both')
                GPIO.output(17, True);
                GPIO.output(18, True);
                sleep(2);
                GPIO.output(17, False);
                GPIO.output(18, False);
        sleep(0.1);

In the code above, one of the settings takes a photo which is saved with a time / date stamp, the other safely shuts the Pi down, and the other is yet to be used.

The easiest way to get your photos off the Pi is to use Filezilla and to connect to your Pi using sFTP – this uses your SSH login and enables you to easily to download and delete photos.

For connecting to your Pi remotely see my previous post about finding your Pi on your network.

I’ve had lots of interesting feedback about the Holga 120d – with the Pi model A (and potentially a smaller model A+ in the works) there are lots of opportunities for adding a digital camera to an existing film camera.

Now i’ve got my Holga 120d up and running I’m going to do some experimenting – my aim being to capture images that you can’t recreate with Instagram. If you’ve got any creative ideas to share please leave them in the comments below!

Raspberry Pi Camera Case – from a Holga

Here’s version 1 of the Holga Raspberry Pi Camera – a hackable, programable camera with a 5 megapixel sensor and HD video capabilities, in retro camera form.

My original concept was to do something like this:

Pi Camera Module camera case sketch
Everything and the kitchen sink

And I managed to build something like this:

Pi Camera Holga Case
And here’s how it turned out..

The Holga is an ultra-cheap medium format camera – if you shop around you can get one for about £15-20 – the model I used for this was the Holga Camera 120N (120 N) (Plastic Lens / Hot Shoe) with the Raspberry Pi Model A – although with a bit of modification it would work with the larger model B. Potentially by soldering the power supply and USB directly to the Pi you could make this a slimmer fit, but I wanted something that didn’t modify the Pi in any way.

The model A Pi fits quite well – you just have to remote the 2 plastic struts inside the case, and peel off the foam that secures the film reels inside the case. I had to remove the plastic panels that enclosed what would have been the flash (my Holga came without one). I cut up a cheap USB extension cable to mount on the top of the camera – and to plug into the side of the Pi. In order to make it fit with the right angled micro USB on the other side I needed to solder and make my own USB cable (you’ll need the shortest USB plug available – I used a poundland retractable USB cable as the source for mine).

If you don’t want to bother with the soldering you could probably just drill holes in either side of the case – there is room, and the plastic is easy to cut through.  

I also added a couple of plastic struts to locate the Pi in place – it’s a snug fit so doesn’t rattle around inside the case.

With the Pi removed you can see how it sits in the camera:

Pi Camera Case without Pi (rear view)
Here it is with all the wires

The yellow wires go to the flash hotshoe – the green to the trigger button on the side of the lens housing, and the red to the power button.

Pi camera case with Pi fitted
Here it’s sitting in it’s case. Snug.

The camera module sits inside the lens with the ribbon cable carefully wrapping around the board and over to the socket – I experimented with Sugru to hold the camera board in place (which would work) but wanted it to be removable, so opted to cut up a piece of spare plastic and drill a hole for the module to peek through – it’s a fairly firm push fit which holds it in place. The lens can still be rotated a little to make it easy to level the Pi camera.

For the power switch I used the same circuit as for the Motorola Lapdock, and added it to the lens mount. I’ve also added a press button on the other side to use to take photos – this will be (eventually) wired to the GPIO.

Pi Camera Detail
Here’s a closeup

Despite it’s cheapness the case feels solid – most of the modifications could be done with a sharp craft knife, apart from a few places where the plastic was thicker or I needed to make holes and a dremel was needed. There’s a lot of empty space inside this case so plenty of room to add things later (I wanted to add a speaker and a few other outputs and inputs, so will do later..)

Overall this was a fun project – all the messy cables and glue are neatly hidden (I went a bit overboard on the glue gun when soldering my USB extension cable) and the case was fairly easy to work with.

The case also has a nice screw mount for a tripod – handy for securing the Pi with camera to things.

Making it more than ‘just a camera’

Replicating a simple Camera with the Pi and Holga (HolgaPi? Piga?) would be a bit boring so my aim with this project is to provide a nice case with the possibility of extending it beyond what I could achieve with a normal compact camera.

At the moment the GPIO isn’t connected to the shutter button or flash trigger – i’ll do this next and write up the method in another blog post.

Things to do:

  • Think of a name
  • Calibrate the viewfinder
  • Write / find some code to make the camera operate over a network. As it lacks a screen the idea of putting all the camera controls into a web app makes sense
  • Add an LED indicator to the viewfinder
  • Add a speaker and think of some sound effects for the camera to make
  • Make use of the flash hotshoe (I’m thinking of using an opto-isolator for this, as some flashes have high trigger voltages running through them)
  • Add some more inputs – this could make the basis of a camera trap. Would be fairly easy to make this rainproof. As it is it would work with a Makey Makey…
  • Write some code to make the GPIO stuff work. I’m relying on this blog post to learn how.
  • Spray it red / green to match with the Pi look, neaten up the lens mount where the glue has discoloured the plastic
  • Investigate batteries or solar power
  • See if I can add a filter mount
  • Send a detailed proposal to the Lomo people to ask them to make a modified Holga case for the Raspberry Pi

Update: check out the following posts in the series.