The advance of digital image in the Museu Picasso

In 2010 I began my activity as Laboratory Technician of Control of the Digital Image in the Centre of Knowledge and Research of the Museu Picasso, as a result of the agreements reached between the museum and the Centre of Image and Multimedia Technology (CITM) of the Polytechnic University of Catalonia (UPC).

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Scheme of a map of bits that simulates the grid of the smallest units of the image.  Each pixel contains R,G,B values.

Among these agreements, a protocol for the reproduction of the original work of Picasso was established. This protocol is very demanding in terms of the quality required of the equipment, the workflow, and the final result of the images, and the need was born for establishing some working criteria at the highest level given that we are talking about protecting and spreading the works of Picasso that the museum holds.

One of the criteria of extreme importance regarding the reproduction of the original work of Picasso is that of maintaining the perception of the colour of the original work in a constant way throughout the workflow between the different devices used . The different nature and construction of these devices generates differences in the interpretation of the colour. The results in the perception of colour are not homogeneous, that is to say, the spaces of colour of the inputs and outputs do not coincide.

Management of colour is concerned with the control of these variations and allows them to establish equivalences between the different languages of interpretation with which each device works – the ICC profiles that we will explain later on.

In a photographic film the smallest unit can be found in the silver halide grain. In digital photography, the smallest unit is the pixel. An image today is an enormous mosaic full of millions of pixels, a map of bits. Each pixel contains the colour information, a sum in different proportions of the primary colours of Red, Green and Blue (RGB). It is a model of colour based on additive synthesis.

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To maintain the perception of the colour of the work we need the ICC profiles of the inputs and outputs that intervene in the digitisation of the original

In digital photography the workflow for reproducing a work of art begins, first of all, with the use of the photographic camera for capturing the image of the object. This input device incorporates a filter called Bayer that allows the RGB signal to be captured and transforms it into an absolute numerical value.  Secondly, we visualize and process the image in the monitor. This output device interprets the absolute value and visualizes an RGB colour. Finally, the processed image reaches an inkjet printer, an output device, which interprets the absolute colour and translates these to the values of Cyan, Magenta, Yellow and Black (CMYK). It is a model of colour based on subtractive synthesis.

The International Colour Consortium created the concept of the ICC profile, both generic and for devices, allowing these changes to be contained in the interpretation and to adjust them in the best possible way to the different readings with which the devices work. It is very important to understand that each ICC profile generated is unique for a specific device and allows the colour of the original work to be preserved.

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The reading is done by means of the spectrophotometer. If the verification is correct we can print the label that confirms the result

The management of the colour programmed in the protocol of the Museu Picasso allows us to create and apply the ICC profiles of inputs and outputs adequately. Once applied, the following step is the process of verification and certification of the colour proof (hard proof). The step consists of validating the results by imitating the output obtained from the printing.  The prints are managed through a RIP software (Rastered Image Processing). This software adds to the task of printing an image, a control strip in the margin of the paper.  The certification of the proofs depends on the results of the reading of the strip.  If the results are positive the verification finishes and the last step is the comparison with the original work.  The image is ready to be sent to the printer.

Nowadays we can say that the protocol for the reproduction of the works that the Museu Picasso applies provides an extremely tight control of the flow of the inputs and outputs of these images and guarantees a faithful reproduction of the works of Picasso in our collection.

Raquel Revuelta
Laboratory Technician of Control of the Digital Image

Related links
The colours of the Picassos or mission impossible

4 Comments
  • Andrés Morón
    December 11, 2014

    Molt i molt interessant!! gracies.
    Per quan una demostració presencial? 😉

  • Raquel
    December 12, 2014

    Moltes gràcies pel teu interès, Andres, i tant de bo que algun dia puguem fer alguna cosa presencial, tot arribarà! 😉

  • Alfonso Quilodran
    January 15, 2016

    Muy buen Trabajo Raquel.
    Felicitaciones!!

  • andres hernandez
    August 25, 2016

    Buenos días.
    Tengo en mi poder desde hace muchos años un cuadro, que no se como explicarlo, no es pintura, mas bien parece una cuadro litografiado, ¿esto tiene algún valor?
    Es un Arlequín de Picasso, Pierrot.
    ¿me pueden decir algo sobre el particular?
    Gracias

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