GB2274563A

GB2274563A - Viewing of colour-negative film

Info

Publication number: GB2274563A
Application number: GB9301393A
Authority: GB
Inventors: William Peter Stuart-Bruges
Original assignee: WILLIAM STUART SYSTEMS Ltd
Current assignee: WILLIAM STUART SYSTEMS Ltd
Priority date: 1993-01-25
Filing date: 1993-01-25
Publication date: 1994-07-27
Also published as: GB9301393D0

Abstract

The colour-negative film 12 is viewed with a domestic video camera 13 whose output is delivered by a converter unit 10 to a television receiver 14. The converter unit 10 includes a light source which is spectrally adjusted to compensate for the colour bias of the film and illuminates a window 11 over which the film is placed. The converter unit 10 also includes the electronic circuitry necessary for inverting the luminance and colour information from the video camera to produce a positive image on the television receiver. <IMAGE>

Description

VIEWING OF COLOUR-NEGATIVE FILM The present invention relates to the viewing of colour-negative film. Such film, from which colour prints are made, is being used on an increasing scale. It suffers from the disadvantage that it is difficult by visual examination of a small negative image to recognize particular shots and to determine whether they are likely to produce a good positive print. This is a particular problem when searching through old negatives.

Since television receivers are almost universally available and the use of domestic video cameras is increasingly common the present invention is based on the idea of using those two pieces of equipment for the purpose of viewing colour negative film. Accordingly the present invention provides apparatus for viewing colour negative film with a domestic video camera, comprising an electronic converter for receiving signals from the video camera and inverting the luminance and colour information in the received signals for display of a positive image on a domestic television receiver, together with a light source for illuminating the colour negative film, the source being spectrally adjusted to compensate for the colour bias of the film.

Preferably the light source is incorporated in the same unit as the electronic converter and illuminates a window over which the film can be placed. The spectral adjustment of the light source can be achieved by selection of a suitable lamp or by using appropriate filters in conjunction with a lamp.

The majority of colour negative films in general use, such as Kodacolor (Registered Trade Mark) film, are processed by the C4l process. They have a pink-orange filter inherent in the film. Thus a unit which incorporates a light source spectrally adjusted to compensate the pink-orange bias will enable a standard video camera and television receiver to produce a full-colour positive image from the majority of colour negative films while using relatively simple electronics to effect the inversion of the colour and luminance information. Without this compensation the processing of the output of the video camera would be complex and expensive and could be impossible if the camera, in attempting to compensate for overall lighting conditions, attenuated the essential colour information.The compensation eliminates the need for elaborate colour correction circuitry, and prevents the camera's built-in colour adjusting circuits from adversely affecting the final image.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: - Figure 1 is a schematic diagram of a unit embodying the invention; Figure 2 is a block diagram of an electronic converter for receiving signals from the video camera; and Figure 3 shows schematicaly apparatus for producing spectrally-adjusted light.

Figure 1 shows schematically the preferred form of a unit in accordance with the invention which includes a box 10 having a window 11 which is illuminated from within by spectrallyadjusted light. A colour negative film 12 to be viewed can simply be placed over the window 11 and appropriate locating and guiding devices for the film may be provided around the window 11. An electronic converter is located within the box which is provided with appropriate terminals for connection to a power source (not shown), a video camera 13, and a television receiver 14.

The video camera 13 is used to view the colour negative film when illuminated by the spectrally adjusted source. The electronic converter receives a composite video input signal from the video camera 13, processes the information received and transmits a signal capable of displaying a positive image on a television receiver 14.

In the electronic converter, the composite video input signal is first broken down by synchronization separation circuitry 20 into: a modified video signal; a blanking signal; a synchronization (sync) signal; and a colour burst signal. The modified video signal, which may or may not be composite, is inverted by an inverter amplifier 21 to give an inverse video signal. The inverter amplifier 21 may include controls for altering the gain, the offset and the colour subcarrier bandpass of the signal. Use of the controls would change respectively the contrast, the brightness and the saturation of the resulting picture received on the television receiver 14.

The inverse video signal is gated with the blanking signal in gate 22 to yield a blanked inverse video signal. The blanked inverse video signal is then recombined at point 23 with the original sync and colour burst signals to provide a composite video output signal suitable for driving the television receiver 14. Alternatively, the composite video output signal may be transmitted by a RF modulator (not shown) to a normal broadcast receiver.

Referring to Figure 3, the spectrally-adjusted light may be produced with apparatus comprising an incandescent source 30, a coloured filter 31 and a diffuser 32. The coloured filter 31 may be fixed and uniform, or alternatively it may be movable and graduated in density, thickness or colour in order to permit spectral adjustment and thereby control the final displayed colour hue. The source 30 may be fluorescent or electroluminescent instead of incandescent. Also, two or more different sources having differing colour spectrums may be used, possibly in conjunction with means for varying their relative brightness.

Claims

CLAIMS:

1. Apparatus for viewing colour-negative film with a video camera, comprising an electronic converter for receiving signals from the video camera and inverting the luminance and colour information in the received signals for display of a positive image on a television receiver, together with a light source for illuminating the colournegative film, the source being spectrally adjusted to compensate for the colour bias of the film.

2. Apparatus as claimed in claim 1 in which the light source is incorporated in the same unit as the electronic converter and illuminates a window over which the film can be placed.

3. Apparatus for viewing colour-negative film with a video camera and displaying a positive image on a television receiver, substantially as described with reference to the accompanying drawings.