One of the most frequent failures in the in vitro trials with Petri dishes is on the photographic registration, since, in its majority, they are carried out in reflective materials, such as plastic, acrylic or, the most common, glass, which depending on the work environment, can suffer luminous interventions. It jeopardizes the image quality and has a negative effect on the obtained results through the experiment or in the results’ confirmation.
The protocol here proposed used a paper tube with a transparent border and emerges as an alternative to correct the previously mentioned mistakes, based on microbiological trials of filamentous fundi in growing process and bacteria on Petri dishes with different means of culture, and the cellphone as image registering equipment, allowing the high quality on the scientific photograph to be reached.
2.1 Necessary Material:
- 01 blurred black sheet of paperboard;
- 01 sheet of transparent material or similar (for example.: plastic bottle, curriculum kind “L” file);
- Cardbox (20 x 20 cm);
- Scissors, white glue, scotch tape, pen and ruler;
- Led ring light;
- black/blue cloth, sulphite paper or a lightbox (x-ray visualizer).
2.2 Procedures for the confection of the paper tube
The PRHQ Protocol consists of the confection of a paper tube, made with black paperboard, whose dimensions may vary according to the size of the Petri dish used in the experiment. The descriptions here presented are valid to trials with glass plates (100x20mm). The images can be obtained with the closed plates (lid and bottom) or open (only the bottom). Obviously, it will affect the tube diameter (Fig1).
- On the blurred black paperboard, cut a rectangle with the proportion of 21 x 33,5 cm, in order to its shape be able to circle all the Peter dish diameter, with a small remnant for the lateral edges fixation;
- On the transparent sheet or similar, cut a piece of ribbon that is, preferable, the same height of the plates (2 x 33,5 cm) and surrounds all of its diameters;
- Through the scotch tape, make a junction of the parts (items a and b) on the larger edge of the rectangle;
- Using an empty Petri dish (of the same dimensions as the ones used in the experiment) as a mold for the desired diameter, so the fixation is done on the lateral edges, forming a tube, maintaining the black side of the paper turned on the inside.
2.3 Procedures for the making of the cellphone framework
The PRHQ protocol adjusts itself mainly to the photographic cameras on cellphones, which have their own settings manually triggered or activated automatically with artificial intelligence sensors, hence, the adjustments on the capture of the image are done at the moment when the photo is taken, in order to obtain a better result.
- Over the paper tube, it is necessary to have a bracket to the cellphone placement, allowing a greater uniformity of the photographic registration; to achieve it, the use of an inflexible material is necessary, such as a cardbox, with the measures of 20 x 20 cm.
- Another square of the same proportions in black paperboard;
- The sides of both squares must be glued, in order to have an entirely black side (paperboard) and another one being the cardbox;
- On the superior side (cardbox), the cellphone placement delimitation is made, from then on, an orifice is opened (only enough) to the camera fitting, which will depend on the cellphone model (Fig2).
2.3 Making of the studio for the photographic registration
The photograph is a result of the performing of several steps, which will guarantee the greater quality of the final image, so the setting environment demands some attention. On the execution of the PRHQ protocol, it is important considering the luminous source and the background.
a) Light: one of the biggest effects expressed on the photo final quality is on the employment of a good luminous source, the main light used on the protocol is a led ring light (Ø 26 cm) without the tripod; its round shape allows a uniform distribution of the light on the Petri dish, revealing many characteristics of the culture or the degradation reaction of the environment, depending on the matter under study. The ring light is positioned with a luminous projection turned to upward (normal), but, depending on the kind of the culture or study focus, this position can be inverted, but, in this case, something to elevate it to a desirable height must be used, usually the same height as of the plate, this way there will be the perfect light crossing (fig3).
b) Background: The culture development over its environment can be better contrasted with the adoption of backgrounds; in this protocol, it is recommended the use of black or blue cloth, sulphite paper sheet or even a lightbox (x-ray visualizer), the choice depends on the culture environment, the colony color and other factors that can affect the contrast. The background works as the backbone for the making of the work studio (led light, Petri dish, tube and cellphone bracket used for its placement). Usually, the black cloth is the most usual and allows great results.
2.5 High-Quality Photograph Register – PRHQ Protocol
After the organization of the whole methodological process for the making of the registration basic structure, the image capturing proceeds. All the exhibited photos were taken with a smartphone, regardless of its brand or model, since there are minimum settings, such as brightness, zoom, focus or other tools that can be used whenever necessary.
This protocol allows that the registration is made, one Petri dish each time, which means, each plate is photographed individually, and it can be representative or, after the registrations, all of them can be put into a group with the help of software or apps, in this way a composed picture is formed or images boards.
The Petri dish with the colony that is desired to take a picture of is put under the black cloth, and, afterwards, the ring light is positioned, considering the plate in the center so the tube is adjusted over the plate, in a perfect fitting, because it was made measured for this arrangement. In the case of a smaller plate, an edge of the cloth will appear at the moment of the register. After the fitting, with the led already turned on, the tube is covered by the cellphone bracket, and the device, on the image capturing mode, is positioned over it, just as the light enters through the transparent border, which allows a greater image quality, without negative influences on the registering act.
After the image capturing, the plate is removed from the tube, in the case, if there is any difficulty in this process, it is recommended that two opposed holes are made on the transparent tape, in order to not go beyond half of its width (≈1 cm) (Fig4).
2.6 Image Editing with Powerpoint tools
Some adjustments, cuts, corrections or layout reviews can be done with specific apps or more practical and accessible software, such as PowerPoint.
This software is meant to design the creation of audiovisual presentations; some tools allow image editing, offering satisfactory results regarding the final quality of the product. One of the main tools is located on the upper tab >>Image Format<<. In order to add it, it is necessary “to copy” the photo that needs editing and “to paste” on the PowerPoint page, afterwards, one must double click on the image to activate the tab >>Image Format<<, usually on the upper right side, the icon >>cut<< can be found, when it is triggered in the photo surroundings and “handles” will come up so one can drag the mouse to erase surplus or undesirable areas (figure 05).
In this same tool, there is the possibility of cutting the picture into the format of basic shapes (as the circular shape). In order to do this, it will be necessary to click on the arrow below the cut icon (˅) and activate the command tab “cut to demarcate shape” and choose which shape is preferable to cut the image. Once the plates are round, the circular one is the most adequate, and it must be selected on the option <<Basic Shapes – Ellipse>>. Afterwards, it is necessary to click on the icon <<cut>> and with the “handles” adjust accordingly the circle, in case it is needed, the size can be adjusted on the “dimension box” besides the cut icon (Fig6).
After the removal of undesired areas from the photograph, it can be saved as an image, clicking with the cursor right button, or it can be kept on PowerPoint to make a montage with other photos from the experiment, forming an image board, which, when it is finished, the pictures can be put into a group, copied and pasted directly on Word or “saved as an image” (Fig7).