Zero-order-hold for two dimensional signal $x(t_1,t_2)$
Yes there exists a 2D analog of the 1D zero order hold for image reconstruction, whose mathematical formulation follows closely that of 1D case as:
$$I_{\mathrm{ZOH}}(x,y)\,= \sum_{n=-\infty}^{\infty} \sum_{m=-\infty}^{\infty} x[n,m]\cdot \operatorname{rect} \left( {x-nT_x,y-mT_y} \right) $$

Where $x[n,m]$ is the spatial samples of 2D image to be reconstructed, $T_x$ and $T_y$ are sampling periods in $x$ and $y$ dimensions (which are generally equal in practice) and the $\operatorname{rect}()$ function is a 2D rectengular pulse of height one and durations $T_x$ and $T_y$ along the dimensions.

The zero order hold interpolation can easily be observed when you enlarge an image through an image editor by not using any smooth interpolation methods but just repeated filling of those new enlarged pixels. 

In particular just use, for example, IrfanView to open any image and choose Image->Resize from menu, then choose to enlarge the image from the options in the coming window, and finally choose "Resize (faster, lo quality)" option from the "Size Methods" sections about lower right corner (for version 4.40)

If you instead choose "smooth" methods, they will fill in the pixels with calculated intermediate values, therefore implementing higher order holds than zero.