optimized fig 4 caption

joss/paper.md

@@ -58,7 +58,7 @@ We compared the resulting PSFs at the focal plane of the telescope, both in the
 
 ![Same as \autoref{fig:benchmark-1}, but adding an optical aberration using Zernike polynomials: 100 nm RMS (WFE) for each of three low-order coefficients in the Zernike expansion: defocus and primary astigmatism (vertical and oblique), corresponding to the coefficients 4, 5, and 6 in the Noll ordering, respectively. The difference between the large-scale features of the PSFs is negligible. \label{fig:benchmark-aberrated-1}](hubble_psf2d_comparison_aberrated.pdf){height=100%}
 
-![Comparison between PSF slices along the x and y axis, respectively. Locally, slightly `hotter` and `colder` pixels can be identified in the PSF wings, although, for powers $\gtrsim$-50 dB, this happens only sporadically. These minute numerical differences may be caused by the different treatment of aperture edges (exact for `PAOS`, sub-pixelled for `PROPER`), causing tiny aliasing errors. \label{fig:benchmark-aberrated-2}](hubble_psf_comparison_aberrated.pdf){height=100%}
+![Comparison between the slices of the aberrated PSFs along the x and y axis, respectively. Locally, slightly `hotter` and `colder` pixels can be identified in the PSF wings, although, for powers $\gtrsim$-50 dB, this happens only sporadically. These minute numerical differences may be caused by the different treatment of aperture edges (exact for `PAOS`, sub-pixelled for `PROPER`), causing tiny aliasing errors. \label{fig:benchmark-aberrated-2}](hubble_psf_comparison_aberrated.pdf){height=100%}
 
 We find that the differences between the aberrated PSFs are negligible and reach peaks of a few dB only in the far wings. However, even in the central region, there is an increase in `hot` and `cold` pixels compared to the unaberrated case. These discrepancies are probably due to the different treatment of the edges of apertures and vanes in the optical system, causing small aliasing errors when not exact. However, they are so tiny that they can be safely neglected for the HST application.