//Write X and Y coordinates of the mouse click to a csv file
        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                System.Drawing.Point point = pictureBox1.PointToClient(Cursor.Position);

                int xPos = (int)(point.X / zoomScale);
                int yPos = (int)(point.Y / zoomScale);
                //Calculate the centroid of the ROI if the auto-centre option is on. Alter the x and y position.
                if (autoCentreCheckBox.Checked)
                {
                    calculateCentrePoint(xPos, yPos, out xPos, out yPos);
                }
                //calculateCentrePoint(point.X, point.Y, out xPos, out yPos);

                //Search the list of output data for a point with the same cell number and picture number. If it exists, replace it with
                //the new point that was just clicked.
                int index = outputData.FindIndex(positionData => positionData != null && positionData.pictureNum == currentImage + 1 &&
                                                 positionData.cell == cellNumber);

                if (index != -1)
                {
                    outputData[index] = new positionData {
                        cell = cellNumber, pictureNum = currentImage + 1, xPosition = xPos, yPosition = yPos
                    };
                }
                else //add the datapoint to the list if it doesn't exist
                {
                    outputData.Add(new positionData
                    {
                        cell       = cellNumber,
                        pictureNum = currentImage + 1,
                        xPosition  = xPos,
                        yPosition  = yPos
                    });
                }
                //Sort the list. First by cell number and then by picture number.
                outputData = outputData.OrderBy(x => x.cell).ThenBy(x => x.pictureNum).ToList();
                //Draw a points and lines connecting
                updateImage();
            }

            //Delete current point if the mouse click was a right click
            else if (e.Button == MouseButtons.Right)
            {
                //Search the list of output data for a point with the same cell number and picture number. If it exists, delete the point
                int index = outputData.FindIndex(positionData => positionData != null && positionData.pictureNum == currentImage + 1 &&
                                                 positionData.cell == cellNumber);
                if (index != -1)
                {
                    outputData.RemoveAt(index); //Delete the point
                    updateImage();
                }
            }
        }
        //Update the image displayed in the picturebox and the "Image: current/total" Label
        //TODO: select the current image on the listboxs
        public void updateImage()
        {
            if (pictureBox1.Image != null)
            {
                pictureBox1.Image.Dispose();
            }

            Image image = Image.FromFile(imageFilePath[currentImage]);

            //Convert if indexed to non-indexed - NOTE: only converts 8bppIndexed right now because I didn't have any other images to test - Jeff 2018/04/14
            if (image.PixelFormat == System.Drawing.Imaging.PixelFormat.Format8bppIndexed)
            {
                pictureBox1.Image = Indexed2Image(image, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
            }
            else
            {
                pictureBox1.Image = image;
            }


            //Draw all the circles of the previous images. For example, if you are on image number 20, it will draw the circles from images 1 to 19
            //Might have performance issues in this method once we start getting to the upper data points
            if (showPrevCheckBox.Checked)
            {
                int xLast = 0, yLast = 0;
                foreach (var prevDataPoint in outputData)
                {
                    //Draw connecting lines to each dot
                    if (prevDataPoint.pictureNum <= currentImage + 1)
                    {
                        DrawCircle(prevDataPoint.xPosition, prevDataPoint.yPosition, prevDataPoint.cell);
                        if (prevDataPoint.pictureNum == 1)
                        {
                            xLast = prevDataPoint.xPosition;
                            yLast = prevDataPoint.yPosition;
                        }
                        else
                        {
                            DrawLine(xLast, yLast, prevDataPoint.xPosition, prevDataPoint.yPosition, prevDataPoint.cell);
                        }
                    }
                    xLast = prevDataPoint.xPosition;
                    yLast = prevDataPoint.yPosition;
                }
            }
            else
            {
                foreach (var prevDataPoint in outputData)
                {
                    if (prevDataPoint.pictureNum == currentImage + 1)
                    {
                        DrawCircle(prevDataPoint.xPosition, prevDataPoint.yPosition, prevDataPoint.cell);
                    }
                }
            }

            //Draw the number of the cell of the last point in each cell number series
            for (int i = 1; i <= totalNumCells; i++)
            {
                positionData lastCellInSeries = new positionData();
                lastCellInSeries = outputData.Where(dataPoint => dataPoint.cell == i).Where(datapoint => datapoint.pictureNum <= currentImage + 1).OrderByDescending(x => x.pictureNum).FirstOrDefault();
                if (lastCellInSeries != null)
                {
                    DrawCell(lastCellInSeries.xPosition, lastCellInSeries.yPosition, lastCellInSeries.cell);
                }
            }

            //Update the image ##/## label
            imageLabel.Text = "Image: " + (currentImage + 1).ToString() + "/" + numImages.ToString();
            //Update the cell # label
            cellNumberLabel.Text = "CELL #: " + cellNumber.ToString();
        }