Why does the image display with reduced quality when scrolling up and down in the report viewer

Dear Sir,

Why does the image display with reduced quality when scrolling up and down in the report viewer?.

Please Guide me.

I have attached the video and image link below.

Video and image

Thanks

Imports Microsoft.Reporting.WinForms

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Me.ReportViewer1.RefreshReport()
        Me.ReportViewer1.SetDisplayMode(Microsoft.Reporting.WinForms.DisplayMode.PrintLayout)
        ReportViewer1.ZoomMode = ZoomMode.Percent
        ReportViewer1.ZoomPercent = 50
    End Sub
End Class